Unit 2 Forces.pdf

9/11/2023 Unit 2 Topics Newton’s Laws of Motion Types of Forces: Weight, Normal For...

9/11/2023 Unit 2 Topics Newton’s Laws of Motion Types of Forces: Weight, Normal Force, Tension Solving Problems with Newton’s Laws: The Method Inclines Unit 2: Dynamics Friction AP Physics C Uniform Circular Motion Mrs. Kelly Air Drag Lab Skill: Linearizing Data 1 2 Why Dynamics? Defining Force Study of forces Force: A push or pull that Kinematics: Describe motion changes an object’s velocity Dynamics: Why is motion? 3 4 Newton’s Laws of Motion Newton’s First Law of Motion Often called the law of inertia: 1. Every object continues in its state of rest, or of uniform velocity in a straight line, as long as no net force acts on it. 5 6 1  9/11/2023 7 8 Newton’s Second Law of Motion Newton’s Third Law of Motion Acceleration is proportional to Whenever one object exerts a force on a second net force and inversely object, the second exerts an equal force in the proportional to mass. opposite direction on the first. (Units of Force?) Newton’s Second Law: 𝐹 = 𝑚𝑎⃗ 𝐹 = 𝑚𝑎⃗ 9 10 11 12 2  9/11/2023 Types of Forces: Weight Types of Forces: Normal Force 𝑭𝒂𝒑𝒑 Weight is the force exerted on an Normal force: Contact force that is object by gravity. exerted perpendicular to the Close to the surface of the Earth, common surface of contact weight is: 𝐹 = 𝑚𝑔⃗ Question: What is the magnitude of the normal force in the picture? (Greater, less than, or equal to mg?) 13 14 Types of Force: Tension Types of Force: Friction Contact force pulling from a string, rope or wire Resists motion Always in direction of string or rope Contact force If rope is massless (usually assumed), tension is constant in the rope Parallel to surfaces More on this later 15 16 Identifying Forces: Practice Homework You are pulling a box along a frictionless Webassign problems surface. The magnitude of the force exerted is 𝐹 = 40.0 N, and it is exerted at a 30.0°angle as shown. Identify all the forces acting on the box in the picture to the right. Be sure to label the forces. If possible, draw vectors indicating the direction of these forces. 17 18 3  9/11/2023 Do-Now: Day 2 Unit 2 Topics You are pulling a box along a frictionless Newton’s Laws of Motion surface. The magnitude of the force Types of Forces: Weight, Normal Force exerted is 𝐹 = 40.0 N, and it is exerted at a 30.0°angle as shown. Solving Problems with Newton’s Laws: The Method Inclines Identify all the forces acting on the box in Friction the picture to the right. Be sure to label Uniform Circular Motion the forces. If possible, draw vectors indicating the direction of these forces. Air Drag Lab Skill: Linearizing Data 19 20 Do-Now: Discussion Dynamics Problems: The Method You are pulling a box along a frictionless 1. Draw a sketch with coordinate system. surface. The magnitude of the force exerted is 𝐹 = 40.0 N, and it is exerted at 2. Draw a free-body diagram. a 30.0°angle as shown. 3. Draw a component diagram: Resolve vectors into components. Identify all the forces acting on the box in the picture to the right. Be sure to label 4. Write Newton’s 2nd Law in vector form. the forces. If possible, draw vectors 5. Write Newton’s 2nd Law in component form. indicating the direction of these forces. 6. Solve. 21 22 Class Problem Force Stations: Using The Method You are pulling a box along a frictionless surface. Use your knowledge of The Method to solve for the missing items at each station. Follow the The magnitude of the force exerted is 𝐹 = directions at each station. 40.0 N, and it is exerted at a 30.0°angle as shown. If the stations are busy, try this problem (Difficulty 2/3): a) Draw the Raw FBD and the component FBD. Two boxes are connected by a lightweight cord and are resting on a table. The boxes have masses of 𝑚 and 𝑚. A variable horizontal force of 𝐹 𝑡 = 𝐶𝑡 is applied by a person to the box with mass Write Newton’s 2nd Law equations (vector 𝑚. Find: and component forms). a) If the boxes start from rest, what are the boxes’ velocities as a function of t? b) Find the acceleration of the box b) The middle string will break when its tension exceeds some tension 𝐹. Find the time will this occur in terms of the given variables. c) The magnitude of the normal force on the box Answers: A) 𝑣 𝑡 = , B) 𝑡 = ( ) 23 24 4  9/11/2023 Worked Example: Try This Group Problem: Try This Draw a free body diagram for the Draw a free body diagram for the two blocks in this diagram. What two blocks in this diagram. What are the possible directions Block are the possible directions Block A can move? A can move? 𝑚 𝑚 Problem: Block A has vertical 𝑚 AND horizontal components of 𝑚 acceleration! (Doable, but messy). 25 26 Dynamics Problems: The Method Group Problem: Variable Force 1. Draw a sketch with coordinate system. Two boxes are connected by a lightweight cord and are resting on a table. The boxes have masses of 12.0 kg and 10.0 kg. A variable horizontal force of 2. Draw a free-body diagram. 𝐹 𝑡 = 𝐵𝑡 is applied by a person to the 10.0 kg box, where B = 5.00 N/s. Find: A. Include + label all forces on object. a) If the boxes start from rest, what are the boxes’ velocities when t = 4 s? B. Magnitudes and directions accurate as possible. C. Multiple objects  separate FBDs. b) The middle string will break when its tension exceeds 100 N. What time will this occur? 3. Resolve vectors into components. 4. Apply Newton’s 2nd law to each component. 5. Solve. 27 28 Homework Do Now: Day 3 Webassign problems We want to develop a model of how the friction force works. Predict which of the following factors will affect the friction force: Object Object Object Surface Object Mass Surface Area Material Material With a partner, design mini-experiments that will test whether the friction force depends on the above variables. For each experiment, design a procedure Surface and discuss your expected results. 29 30 5  9/11/2023 Unit 2 Topics Newton’s Laws of Motion Types of Forces: Weight, Normal Force Solving Problems with Newton’s Laws: The Method Inclines Homework Discussion Friction Uniform Circular Motion Air Drag Lab Skill: Linearizing Data 31 32 Defining Friction 𝑭𝑷 Modeling Friction Force that resists relative motion of surfaces Object Question: Suppose the block to the right is traveling at a constant velocity under Object Object Object Surface an applied force 𝐹. What is the Surface Mass Material Material direction of the friction force? Area What is the magnitude of the friction Surface force? 33 34 4-8 Applications Involving Friction, Inclines Modeling Sliding Friction Kinetic Friction 𝐹 =𝜇 𝐹 𝐹 = Normal Force 𝜇 = Coefficient of kinetic friction (depends on object/surface material) Friction opposes direction of motion 35 36 6  9/11/2023 Modeling Static Friction Static Friction 𝐹 ≤𝜇 𝐹 𝐹 = Normal Force 𝜇 = Coefficient of kinetic friction (object/surface material) External forces must overcome static friction to make object to move 37 38 39 40 Class Problem A box rests on a rough 30.0° incline. a) Draw a free-body diagram, showing all the forces acting on the box. b) How would the diagram change if the box were sliding down the plane? c) How would it change if the box were sliding up the plane after an initial shove? d) Suppose the coefficient of static friction between the block and ramp is 𝜇. At what angle does the block start to slide? 41 42 7  9/11/2023 Mini-Lab Now: Demonstrations Find 𝜇 and 𝜇 for the block-track system. Sit and Spin Test your prediction! At what angle does the block start to slide? Cup of water on a string 43 44 Uniform Circular Motion Uniform circular motion: motion in a circle of constant radius at constant speed 45 46 Acceleration in UCM Summary: Centripetal Acceleration Centripetal Acceleration 𝑣 𝑎 = − 𝑟̂ 𝑟 Objects in UCM have centripetal acceleration Acceleration points toward center of circle (−𝑟̂ direction) 𝑟̂ 47 48 8  9/11/2023 More UCM Quantities Class Problem v Quantity Variable/Formula Description A 150-g ball at the end of a string is revolving uniformly in a vertical on the end Frequency 𝑓 Revolutions per second of a 1.10-m cord. The ball is moving at a speed of 6.56 m/s. a) What is the tension of the cord at the R 1 bottom of the arc? Period 𝑇= Time to complete 1 revolution 𝑓 b) What is the tension of the cord in the top of the arc? 2𝜋𝑟 Speed 𝑣= 1 circumference per period 𝑇 49 50 Do-Now: Day 5 A 1000-kg car rounds on a curve on a flat road of radius 50 m at a speed of 14 m/s. a) What is the minimum possible coefficient of static friction for the car to make this turn? b) What is the maximum speed possible Homework Discussion on this curve if the pavement is icy and 𝜇 =0.25? 51 52 Unit 2 Topics Do-Now: Discussion Newton’s Laws of Motion A 1000-kg car rounds on a curve on a flat Types of Forces: Weight, Normal Force road of radius 50 m at a speed of 14 m/s. Solving Problems with Newton’s Laws: The Method a) What is the minimum possible coefficient of static friction for the car to Inclines make this turn? Friction b) What is the maximum speed possible on this curve if the pavement is icy and Uniform Circular Motion 𝜇 =0.25? Air Drag Lab Skill: Linearizing Data 53 54 9  9/11/2023 UCM Application: Banked Turns 𝐹 𝐹 𝐹 𝐹 𝐹 𝑚𝑔 𝑚𝑔 𝑚𝑔 A B C 55 56 y y 𝐹 x x A B y x x 𝑚𝑔 y C D 57 58 59 60 10  9/11/2023 Class Problem Class Problem A curve with a radius of 100 m is banked at 15°. The road is icy, so A curve with a radius of 100 m is banked at 15°. The road is icy, so there is no frictional force on the tires. there is no frictional force on the tires. a. What is the appropriate speed to traverse this curve? a. What is the appropriate speed to traverse this curve? b. The ice melts, and the car can navigate the curve at 25 m/s. Draw and label the forces on the car. c. What is the minimum coefficient of static friction needed for the car to round the curve at 25 m/s? 61 62 Do-Now: Day 6 A cart is released from rest at the top of a ramp. An experimental system measures the cart’s speed at different points along the ramp. a. Download the data on the class website. Create a graph of the independent variable vs. the dependent variable. What type of graph is this? (Linear, quadratic, exponential, etc.?) b. Discuss: Is it possible to find the acceleration solely from these data? If so, explain how. If not, explain what information you need. Homework Discussion Photogates (measure speed) 63 64 Unit 2 Topics Do-Now: Discussion Newton’s Laws of Motion A cart is released from rest at the top of a ramp. An experimental system measures the cart’s speed at different displacements along the ramp. Types of Forces: Weight, Normal Force a. Download the data on the class website. Create a graph of the independent Solving Problems with Newton’s Laws: The Method variable vs. the dependent variable. What type of graph is this? (Linear, quadratic, exponential, etc.?) Inclines b. Discuss: Is it possible to find the acceleration solely from these data? If so, Friction explain how. If not, explain what information you need. Uniform Circular Motion Photogates (measure speed) Lab Skill: Linearizing Data Air Drag 65 66 11  9/11/2023 Skill: Data Linearization Now: Air Resistance Linearizing Data = Adjusting the variables so that you can graph a What do we know about air straight line. resistance? Use slope and/or intercepts to calculate physical quantities. How does motion with air Why? resistance differ from motion Linear graphs are easy. without air resistance? Accounts for variation across trials What factors might affect air This is on the AP resistance? For our Do-Now: What equation relates ∆𝑥 and 𝑣? (Assume constant acceleration). 67 68 Lab: Developing a Model of Air Resistance Goal: develop an equation to for the drag force on a set of coffee filters. 69 12  2017 AP® PHYSICS C: MECHANICS FREE-RESPONSE QUESTIONS PHYSICS C: MECHANICS SECTION II Time—45 minutes 3 Questions Directions: Answer all three questions. The suggested time is about 15 minutes for answering each of the questions, which are worth 15 points each. The parts within a question may not have equal weight. Show all your work in this booklet in the spaces provided after each part. 1. An Atwood’s machine consists of two blocks connected by a light string that passes over a frictionless pulley of negligible mass, as shown in the figure above. The masses of the two blocks, M1 and M 2 , can be varied. M 2 is always greater than M1. (a) On the dots below, which represent the blocks, draw and label the forces (not components) that act on the blocks. Each force must be represented by a distinct arrow starting on and pointing away from the appropriate dot. The relative lengths of the arrows should show the relative magnitudes of the forces. (b) Using the forces in your diagrams above, write an equation applying Newton’s second law to each block and use these two equations to derive the magnitude of the acceleration of the blocks and show that it is given by M2 M1 the equation: a g M1 M2 © 2017 The College Board. Visit the College Board on the Web: www.collegeboard.org. GO ON TO THE NEXT PAGE. -5-  2017 AP® PHYSICS C: MECHANICS FREE-RESPONSE QUESTIONS The magnitude of the acceleration a was measured for different values of M1 and M 2 , and the data are shown below. M1 (kg) 1.0 2.0 5.0 6.0 10.0 M 2 (kg) 2.0 3.0 12.0 8.0 14.0 a (m/s2) 3.02 1.82 4.21 1.15 1.71 (c) Indicate below which quantities should be graphed to yield a straight line whose slope could be used to calculate a numerical value for the acceleration due to gravity g. Vertical axis: Horizontal axis: Use the remaining rows in the table above, as needed, to record any quantities that you indicated that are not given. (d) Plot the data points for the quantities indicated in part (c) on the graph below. Clearly scale and label all axes including units, if appropriate. Draw a straight line that best represents the data. (e) Using your straight line, determine an experimental value for g. © 2017 The College Board. Visit the College Board on the Web: www.collegeboard.org. GO ON TO THE NEXT PAGE. -6-  2017 AP® PHYSICS C: MECHANICS FREE-RESPONSE QUESTIONS The experiment is now repeated with a modification. The Atwood’s machine is now set up so that the block of mass M1 is on a smooth, horizontal table and the block of mass M 2 is hanging over the side of the table, as shown in the figure above. (f) For the same values of M 1 and M 2 , is the magnitude of the tension in the string when the blocks are moving higher, lower, or equal to the magnitude of the tension in the string when the blocks are moving in the first experiment? ____ Higher ____ Lower ____ Equal to Justify your answer. (g) The value determined for the acceleration due to gravity g is lower than in the first experiment. Give one physical factor that could account for this lower value and explain how this factor affected the experiment. © 2017 The College Board. Visit the College Board on the Web: www.collegeboard.org. GO ON TO THE NEXT PAGE. -7- 10/2/24, 11:22 PM 24-25 PS 09 - Forces Review (Optional) - TJ007, section Smith 1 | WebAssign EN [email protected] (Sign out) Home My Assignments Grades Communication Calendar My eBooks TJ007, section Smith 1, INSTRUCTOR 24-25 PS 09 - Forces Review Adam Smith Thomas Jefferson HS - Science & (Optional) (Homework) Technology, VA Current Score QUESTION 1 2 3 4 5 6 TOTAL SCORE POINTS –/1 –/3 –/2 –/2 –/2 –/1 –/11 0.0% Due Date Past Due MON, SEP 23, 2024 10:00 PM EDT Request Extension Assignment Submission & Scoring Assignment Submission https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715056 1/5 10/2/24, 11:22 PM 24-25 PS 09 - Forces Review (Optional) - TJ007, section Smith 1 | WebAssign For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your best submission for each question part is used for your score. The due date for this assignment has passed. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension View Key 1. [–/1 Points] DETAILS MY NOTES HRW10 6.P.069. ASK YOUR TEACHER PRACTICE ANOTHER A student, crazed by final exams, uses a force of magnitude 88 N and angle 𝜃 = 70° to push a 5.3 kg block across the ceiling of his room, as shown below. If the coefficient of kinetic friction between the block and the ceiling is 0.45, what is the magnitude of the block's acceleration? (No Response) m/s2 Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715056 2/5 10/2/24, 11:22 PM 24-25 PS 09 - Forces Review (Optional) - TJ007, section Smith 1 | WebAssign 2. [–/3 Points] DETAILS MY NOTES HRW10 6.P.071. ASK YOUR TEACHER PRACTICE ANOTHER A 7.70 kg block of steel is at rest on a horizontal table. The coefficient of static friction between the block and the table is 0.500. A force is to be applied to the block. To three significant figures, what is the magnitude of that applied force if it puts the block on the verge of sliding when the force is directed in the following directions? (a) horizontally (No Response) N (b) upward at 56.0° from the horizontal (No Response) N (c) downward at 56.0° from the horizontal (No Response) N Additional Materials eBook 3. [–/2 Points] DETAILS MY NOTES HRW10 6.P.078. ASK YOUR TEACHER PRACTICE ANOTHER A student wants to determine the coefficients of static friction and kinetic friction between a box and a plank. She places the box on the plank and gradually raises one end of the plank. When the angle of inclination with the horizontal reaches 35°, the box starts to slip, and it slides 2.4 m down the plank in 3.8 s at constant acceleration. (a) What is the coefficient of static friction? (No Response) (b) What is the coefficient of kinetic friction? (No Response) Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715056 3/5 10/2/24, 11:22 PM 24-25 PS 09 - Forces Review (Optional) - TJ007, section Smith 1 | WebAssign 4. [–/2 Points] DETAILS MY NOTES HRW10 6.P.081.SSM. ASK YOUR TEACHER PRACTICE ANOTHER A bicyclist travels in a circle of radius 32.0 m at a constant speed of 5.00 m/s. The bicycle-rider mass is 80.0 kg. (a) Calculate the magnitude of the force of friction on the bicycle from the road. (No Response) N (b) Calculate the magnitude of the net force on the bicycle from the road. (No Response) N Additional Materials eBook 5. [–/2 Points] DETAILS MY NOTES HRW10 6.P.086. ASK YOUR TEACHER PRACTICE ANOTHER A sling-thrower puts a stone (0.250 kg) in the sling's pouch (0.010 kg) and then begins to make the stone and pouch move in a vertical circle of radius 0.695 m. The cord between the pouch and the person's hand has negligible mass and will break when the tension in the cord is 30.0 N or more. Suppose the sling-thrower could gradually increase the speed of the stone. (a) Will the breaking occur at the lowest point of the circle or at the highest point? lowest point highest point (b) At what speed of the stone will that breaking occur? (No Response) m/s Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715056 4/5 10/2/24, 11:22 PM 24-25 PS 09 - Forces Review (Optional) - TJ007, section Smith 1 | WebAssign 6. [–/1 Points] DETAILS MY NOTES HRW10 6.P.088. ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, block 1 of mass m1 = 5.0 kg and block 2 of mass m2 = 4.0 kg are connected by a string of negligible mass. Block 2 is pushed by force F of magnitude 25 N and angle 𝜃 = 30°. The coefficient of kinetic friction between each block and the horizontal surface is 0.10. What is the tension in the string? (No Response) N Additional Materials eBook Home My Assignments Request Extension Copyright © 1998 - 2024 Cengage Learning, Inc. All Rights Reserved TERMS OF USE PRIVACY https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715056 5/5 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign EN [email protected] (Sign out) Home My Assignments Grades Communication Calendar My eBooks TJ007, section Smith 1, INSTRUCTOR 24-25 PS 08 - UCM and Multi-Body Adam Smith Thomas Jefferson HS - Science Systems (Homework) & Technology, VA Current Score QUESTION 1 2 3 4 5 6 TOTAL SCORE POINTS 1/1 –/4 0/2 –/2 –/2 –/1 1/12 8.3% Due Date Past Due SUN, SEP 22, 2024 10:00 PM EDT Request Extension Assignment Submission & Scoring Assignment Submission https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 1/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your best submission for each question part is used for your score. The due date for this assignment has passed. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension 1. [1/1 Points] DETAILS MY NOTES HRW10 6.P.057.GO. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A puck of mass m = 1.45 kg slides in a circle of radius r = 23.0 cm on a frictionless table while attached to a hanging cylinder of mass M = 2.40 kg by a cord through a hole in the table. What speed keeps the cylinder at rest? 1.93 1.93 m/s GO Tutorial Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 2/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign 2. [–/4 Points] DETAILS MY NOTES HRW10 6.P.068. ASK YOUR TEACHER PRACTICE ANOTHER If a car goes through a curve too fast, the car tends to slide out of the curve. For a banked curve with friction, a frictional force acts on a fast car to oppose the tendency to slide out of the curve; the force is directed down the bank (in the direction water would drain). Consider a circular curve of radius R = 230 m and bank angle 𝜃, where the coefficient of static friction between tires and pavement is 𝜇s. A car (without negative lift) is driven around the curve as shown in the figure below. (a) Find an expression for the car speed vmax that puts the car on the verge of sliding out. (Use any variable or symbol stated above along with the following as necessary: g for the acceleration of gravity. Do not substitute numerical values; use variables only.) vmax = (No Response) (b) On the same graph, plot vmax versus angle 𝜃 for the range 0° to 50°, first for 𝜇s = 0.58 (dry pavement) and then for 𝜇s = 0.320 (wet or icy pavement). Key: File upload This answer has not been graded yet. (c) In kilometers per hour, evaluate vmax for a bank angle of 𝜃 = 4° and 𝜇s = 0.58. (No Response) 141 km/h (d) In kilometers per hour, evaluate vmax for a bank angle of 𝜃 = 4° and 𝜇s = 0.320. (No Response) 108 km/h (Now you can see why accidents occur in highway curves when wet or icy conditions are not obvious to drivers, who tend to drive at normal speeds.) Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 3/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign 3. [0/2 Points] DETAILS MY NOTES HRW10 6.P.095. PREVIOUS ANSWERS ASK YOUR TEACHER In the figure below a fastidious worker pushes directly along the handle of a mop with a force. The handle is at an angle 𝜃 with the vertical, and 𝜇s and 𝜇k are the coefficients of static and kinetic friction between the head of the mop and the floor. Ignore the mass of the handle and assume that all the mop's mass m is in its head. (a) If the mop head moves along the floor with a constant velocity, then what is F? (Use any variable or symbol stated above along with the following as necessary: g for the acceleration due to gravity.) F= $$μkmgsin(θ)−μkcos(θ) (b) Show that if is less than a certain value 𝜃0, then (still directed along the handle) is unable to move the mop head. Find 𝜃0. (Use any variable or symbol stated above along with the following as necessary: g for the acceleration due to gravity.) 𝜃0 = $$tan−1(μs) Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 4/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign 4. [–/2 Points] DETAILS MY NOTES HRW10 6.P.075. ASK YOUR TEACHER PRACTICE ANOTHER A locomotive accelerates a 25-car train along a level track. Every car has a mass of 6.0 ✕ 104 kg and is subject to a friction force f = 250v where the speed v is in meters per second and the force f is in newtons. At the instant when the speed of the train is 40 km/h, the magnitude of the acceleration is 0.20 m/s2. (a) What is the tension in the coupling between the first car and the locomotive? (No Response) 3.69e+05 N (b) If the tension is equal to the maximum force the locomotive can exert on the train, what is the steepest grade up which the locomotive can pull the train at 40 km/h? (No Response) 1.17 ° Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 5/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign 5. [–/2 Points] DETAILS MY NOTES HRW10 6.P.061.SSM. ASK YOUR TEACHER PRACTICE ANOTHER A block of mass mt = 4.0 kg is put on top of a block of mass mb = 7.5 kg. To cause the top block to slip on the bottom one, while the bottom one is held fixed, a horizontal force of at least 20 N must be applied to the top block. The assembly of blocks is now placed on a horizontal, frictionless table. (a) Find the magnitude of the maximum horizontal force that can be applied to the lower block so that the blocks will move together. (No Response) 57.5 N (b) Find the magnitude of the resulting acceleration of the blocks. (No Response) 5 m/s2 Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 6/7 10/2/24, 11:22 PM 24-25 PS 08 - UCM and Multi-Body Systems - TJ007, section Smith 1 | WebAssign 6. [–/1 Points] DETAILS MY NOTES HRW10 6.P.066. ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, block 1 of mass m1 = 1.00 kg and block 2 of mass m2 = 2.00 kg are connected by a string of negligible mass and are initially held in place. Block 2 is on a frictionless surface tilted at 𝜃 = 30°. The coefficient of kinetic friction between block 1 and the horizontal surface is 0.17. The pulley has negligible mass and friction. Once they are released, the blocks move. What then is the tension in the string? (No Response) 4.38 N Additional Materials eBook Home My Assignments Request Extension Copyright © 1998 - 2024 Cengage Learning, Inc. All Rights Reserved TERMS OF USE PRIVACY https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715040 7/7 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign EN [email protected] (Sign out) Home My Assignments Grades Communication Calendar My eBooks TJ007, section Smith 1, INSTRUCTOR 24-25 PS 07 - Forces in Circular Adam Smith Thomas Jefferson HS - Science & Motion (Homework) Technology, VA Current Score QUESTION 1 2 3 4 5 TOTAL SCORE POINTS 1/1 3/3 4/4 1/1 2/2 11/11 100.0% Due Date Past Due WED, SEP 18, 2024 10:00 PM EDT Request Extension Assignment Submission & Scoring Assignment Submission https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 1/6 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your best submission for each question part is used for your score. The due date for this assignment has passed. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension View Key 1. [1/1 Points] DETAILS MY NOTES HRW10 6.P.041. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A cat dozes on a stationary merry-go-round, at a radius of 5.2 m from the center of the ride. Then the operator turns on the ride and brings it up to its proper turning rate of one complete rotation every 7.0 s. What is the least coefficient of static friction between the cat and the merry-go-round that will allow the cat to stay in place, without sliding? 0.43 Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 2/6 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign 2. [3/3 Points] DETAILS MY NOTES HRW10 6.P.054. PREVIOUS ANSWERS ASK YOUR TEACHER In designing circular rides for amusement parks, mechanical engineers must consider how small variations in certain parameters can alter the net force on a passenger. Consider a passenger of mass m riding around a horizontal circle of radius r at speed v. What is the variation dF in the net force magnitude for the following? (a) A variation dr in the radius with v held constant? (Use any variable or symbol stated above as necessary.) dF = $$−mv2r2dr (b) A variation dv in the speed with r held constant? (Use any variable or symbol stated above as necessary.) dF = $$2mvrdv (c) A variation dT in the period with r held constant? (Use any variable or symbol stated above as necessary.) dF = $$−mv3πr2dT Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 3/6 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign 3. [4/4 Points] DETAILS MY NOTES HRW10 6.P.059.SSM. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, a 1.35 kg ball is connected by means of two massless strings, each of length L = 1.70 m to a vertical, rotating rod. The strings are tied to the rod with separation d = 1.70 m and are taut. The tension in the upper string is 37 N. (a) What is the tension in the lower string? 10.5 N (b) What is the speed of the ball? 6.70 m/s (c) What is the magnitude of the net force net on the ball? 41.1 N (d) What is the direction of net? (0° means radially inwards.) 0 ° Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 4/6 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign 4. [1/1 Points] DETAILS MY NOTES HRW10 6.P.049. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, a car is driven at constant speed over a circular hill and then into a circular valley with the same radius. At the top of the hill, the normal force on the driver from the car seat is 0. The driver's mass is 82.0 kg. What is the magnitude of the normal force on the driver from the seat when the car passes through the bottom of the valley? 1608 N Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 5/6 10/2/24, 11:22 PM 24-25 PS 07 - Forces in Circular Motion - TJ007, section Smith 1 | WebAssign 5. [2/2 Points] DETAILS MY NOTES HRW10 6.P.070. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER The figure below shows a "conical pendulum", in which the bob (the small object at the lower end of the cord) moves in a horizontal circle at constant speed. (The cord sweeps out a cone as the bob rotates.) The bob has a mass of 0.050 kg, the string has length L = 0.54 m and negligible mass, and the bob follows a circular path of circumference 0.90 m. (a) What is the tension in the string? 0.508 N (b) What is the period of the motion? 1.45 s Additional Materials eBook Home My Assignments Request Extension Copyright © 1998 - 2024 Cengage Learning, Inc. All Rights Reserved TERMS OF USE PRIVACY https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35715017 6/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign EN [email protected] (Sign out) Home My Assignments Grades Communication Calendar My eBooks TJ007, section Smith 1, INSTRUCTOR 24-25 PS 06 - Friction Adam Smith Thomas Jefferson HS - Science & (Homework) Technology, VA Current Score QUESTION 1 2 3 4 5 6 TOTAL SCORE POINTS 1/1 1/1 2/2 2/2 2/2 1/1 9/9 100.0% Due Date Past Due SUN, SEP 15, 2024 10:00 PM EDT Request Extension Assignment Submission & Scoring Assignment Submission https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 1/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your best submission for each question part is used for your score. The due date for this assignment has passed. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension View Key 1. [1/1 Points] DETAILS MY NOTES HRW10 6.P.001. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER The floor of a railroad flatcar is loaded with loose crates having a coefficient of static friction of 0.21 with the floor. If the train is initially moving at a speed of 49 km/h, in how short a distance can the train be stopped at constant acceleration without causing the crates to slide over the floor? 45.0 m Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 2/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign 2. [1/1 Points] DETAILS MY NOTES HRW10 6.P.004. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A slide loving pig slides down a certain 29° slide in twice the time it would take to slide down a frictionless 29° slide. What is the coefficient of kinetic friction between the pig and the slide? 0.42 Additional Materials eBook 3. [2/2 Points] DETAILS MY NOTES HRW10 6.P.011.SSM. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A 63 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 13° above the horizontal. (a) If the coefficient of static friction is 0.49, what minimum force magnitude is required from the rope to start the crate moving? 279 N (b) If 𝜇k = 0.34, what is the magnitude of the initial acceleration of the crate? 1.32 m/s2 Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 3/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign 4. [2/2 Points] DETAILS MY NOTES HRW10 6.P.018. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER You testify as an expert witness in a case involving an accident in which car A slid into the rear of car B, which was stopped at a red light along a road headed down a hill. You find that the slope of the hill is 𝜃 = 11.5°, that the cars were separated by distance d = 26.5 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 = 16.0 m/s. (a) With what speed did car A hit car B if the coefficient of kinetic friction was 0.60 (dry road surface)? 7.36 m/s (b) What was the speed if the coefficient of kinetic friction was 0.10 (road surface covered with wet leaves)? 17.6 m/s Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 4/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign 5. [2/2 Points] DETAILS MY NOTES HRW10 6.P.019. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A 15 N horizontal force pushes a block weighing 6.0 N against a vertical wall. The coefficient of static friction between the wall and the block is 0.73, and the coefficient of kinetic friction is 0.53. Assume that the block is not moving initially. (a) Will the block move? Yes No (b) In unit-vector notation, what is the force exerted on the block by the wall? $$−15i+6j N Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 5/6 10/2/24, 11:22 PM 24-25 PS 06 - Friction - TJ007, section Smith 1 | WebAssign 6. [1/1 Points] DETAILS MY NOTES HRW10 6.P.025.SSM. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER Block B in the figure below weighs 716 N. The coefficient of static friction between block and table is 0.18; angle 𝜃 is 24°; assume that the cord between B and the knot is horizontal. Find the maximum weight of block A for which the system will be stationary. 57.3 N Additional Materials eBook Home My Assignments Request Extension Copyright © 1998 - 2024 Cengage Learning, Inc. All Rights Reserved TERMS OF USE PRIVACY https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714996 6/6 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign EN [email protected] (Sign out) Home My Assignments Grades Communication Calendar My eBooks TJ007, section Smith 1, INSTRUCTOR 24-25 PS 05 - Introduction to Adam Smith Thomas Jefferson HS - Science & Forces (Homework) Technology, VA Current Score QUESTION 1 2 3 4 5 TOTAL SCORE POINTS 3/3 2/2 2/2 3/3 3/3 13/13 100.0% Due Date Past Due WED, SEP 11, 2024 10:00 PM EDT Request Extension Instructions Assignment Submission & Scoring Assignment Submission https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 1/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign This assignment requires a thorough reading of Chapter 3 For this assignment, you submit in your textbook, as well as sections 5-1 and 5-2 of Chapter answers by question parts. The 5. number of submissions remaining for each question part only changes if you submit or change the answer. Assignment Scoring Your best submission for each question part is used for your score. The due date for this assignment has passed. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension View Key https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 2/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign 1. [3/3 Points] DETAILS MY NOTES HRW10 5.P.017.SSM. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER Refer to the figure below. Let the mass of the block be 9.5 kg and the angle 𝜃 be 30°. (a) Find the tension in the cord. 46.6 N (b) Find the normal force acting on the block. 80.7 N (c) If the cord is cut, find the magnitude of the resulting acceleration of the block. 4.9 m/s2 Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 3/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign 2. [2/2 Points] DETAILS MY NOTES HRW10 5.P.034.GO. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, a crate of mass m = 120 kg is pushed at constant speed up the frictionless ramp (𝜃 = 28.0°) by a horizontal force. (a) What is the magnitude of ? 625 N (b) What is the force on the crate from the ramp? (Enter the magnitude.) 1332 N GO Tutorial Additional Materials eBook https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 4/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign 3. [2/2 Points] DETAILS MY NOTES HRW10 5.P.039. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A sphere of mass 3.8 ✕ 10-4 kg is suspended from a cord. A steady horizontal breeze pushes the sphere so that the cord makes a constant angle of 46° with the vertical. (a) Find the magnitude of that push. 0.00385 N (b) Find the tension in the cord. 0.00536 N Additional Materials eBook Algebra-Squareroots & Squares https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 5/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign 4. [3/3 Points] DETAILS MY NOTES HRW10 5.P.049. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, a block of mass 3.90 kg is pulled along a horizontal frictionless floor by a cord that exerts a force = 14.3 N at an angle 𝜃 = 25.0° above the horizontal. (a) What is the magnitude of the block's acceleration? 3.32 m/s2 (b) The force magnitude F is slowly increased. What is its value just before the block is lifted (completely) off the floor? 90.4 N (c) What is the magnitude of the acceleration of the block just before it is lifted (completely) off the floor? 21.0 m/s2 Additional Materials eBook Algebra-Squareroots & Squares https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 6/7 10/2/24, 11:21 PM 24-25 PS 05 - Introduction to Forces - TJ007, section Smith 1 | WebAssign 5. [3/3 Points] DETAILS MY NOTES HRW10 5.P.031.SSM. PREVIOUS ANSWERS ASK YOUR TEACHER PRACTICE ANOTHER A block is projected up a frictionless inclined plane with initial speed v0 = 3.41 m/s. The angle of incline is 𝜃 = 31.4°. (a) How far up the plane does the block go? 1.14 m (b) How long does it take to get there? 0.667 s (c) What is its speed when it gets back to the bottom? 3.41 m/s Additional Materials eBook Home My Assignments Request Extension Copyright © 1998 - 2024 Cengage Learning, Inc. All Rights Reserved TERMS OF USE PRIVACY https://www.webassign.net/web/Student/Assignment-Responses/last?dep=35714984 7/7