Phys 125 Practice Exam 1.pdf

Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM PHYS 125, Exam 1, Fall 2020  This is a preview of the published version of the quiz Started: Aug 30 at 2:30pm Quiz Instructions https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 1...

Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM PHYS 125, Exam 1, Fall 2020  This is a preview of the published version of the quiz Started: Aug 30 at 2:30pm Quiz Instructions https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 1 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM 1. This exam has 25 questions. You have 2 hours to complete it, which will be enforced by Canvas. The exam is all multiple choice. When you open it, you will see all of the questions at once. For questions that share a figure, the figure and description are copied for each question. This is not a mistake. It is intended to make sure you don't get confused about which figure goes with each question. 2. You will see the entire exam in a single window. Scroll through it to enter your answers. You can change them as you go because YOU ONLY CLICK "SUBMIT" ONE TIME WHEN YOU ARE FINISHED. 3. This exam is pledged and you are to take it under typical conditions. The exam is NOT open book or open note. You may only use your calculator and the formula sheet. Rather than signing the pledge, by beginning the exam you are acknowledge that you will follow the honor code. 4. You may use the formula sheet posted on Canvas. To do so we suggest you open it in another tab, or print it out. 5. We will not issue clarifications while the exam is out. If something is unclear you can email "[email protected]", but we will not respond. These messages will be collected and used to decide if any adjustments need to be applied to the grading of the exam (such as throwing a question out or taking two answers). 6. If you experience a signficant problem such as scrambled equations from your browser, loss of internet connection, loss of power, bear attack, etc., stop taking the exam, note how much time you have used, and then email "[email protected]" and we will make a plan for you to finish the exam. 7. In addition to the electronic submission, keep a paper answer sheet that you can send us if there is a problem with Canvas submission. It just needs your answer for each problem (letter and value), not all of your work. For example: 1. C, 90 V; 2. B, up; 3. A, 7 mA,... 8. When you click submit, Canvas will automatically grade it, but that is not your score! We have set all answers to "A" so that you will not know which you got right and wrong until we put in the correct answers and re-grade it. We will do this once all students have taken the exam. 9. Good luck! Question 1 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 2 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM Can an object simultaneously (1) have an acceleration that is positive along a 1D axis and (2) be slowing down? Here “slowing down” means that the magnitude of the object’s velocity vector is decreasing with time. A. No B. Yes Question 2 1 pts Kinematics graphs for three drag racers are shown below. At the final time, tf, which racer has traveled the farthest? A B C D. All have traveled the same distance. https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 3 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM Question 3 1 pts You launch two 3 kg masses from the ground. The first has an initial velocity of 12 m/s and the second 9 m/s. How much higher does the first mass go than the second mass (but not necessarily hitting their peak at the same time)? A. 7.1 m B. 4.1 m C. 3.2 m D. 1.6 m E. 0.15 m Question 4 1 pts The complicated one-dimensional motion of an object with “jerk” (a changing acceleration) is described by the following expression for position: x = 4 + 3t -9.8t2 + 1.2t3 The constants are in standard units: 4 m, 3 m/s, -9.8 m/s2, and 1.2 m/s3. What is the velocity of the object at t = 3 s? A. 94.2 m/s B. 9 m/s C. 0 m/s https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 4 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM D. -23.4 m/s E. -42.8 m/s Question 5 1 pts Changing which of the following will not affect the final position of a projectile? A. Initial speed B. Initial Angle C. Gravitational acceleration D. Projectile mass Question 6 1 pts At a baseball game you notice that a ball hit deep into center field is in flight for a time T. Assuming it launched at and landed at the same height, how high did it go? Ignore air resistance. A. gT2 B. 2gT2 C. 4gT2 D. 8gT2 2 https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 5 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM E. gT2/2 F. gT2/4 G. gT2/8 Question 7 1 pts You fire two projectiles simultaneously from launchers that have fixed angles but adjustable launch velocities. The launchers are fixed at 45 degrees and 30 degrees above the horizontal. You want the projectiles to land the same distance from the launchers. What ratio of initial velocity magnitudes do you need? The answers below are defined as vi-30 / vi-45 ? A. 0.93 B. 1.00 C. 1.07 D. 1.15 E. 1.70 F. 2.30 Question 8 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 6 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM You drop a 5 kg ball from a height of 30 m. You can ignore air resistance along the vertical axis as usual. However, there is a strong wind that applies a constant 12 N horizontal force to the ball. How far does the wind blow the ball? That is, how far does the ball land from the place it would have landed if there were no wind? A. 0.0 m B. 0.7 m C. 3.1 m D. 7.3 m E. 14.6 m F. 36.7 m Question 9 1 pts You drive down the road as rain drops fall straight down (straight down in the ground frame). The drops fall at a constant 8 m/s in the ground frame due to air resistance. From inside the car, the drops appear to fall at 60 degrees from the vertical direction. How fast are you driving? A. 0 m/s B. 4.6 m/s https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 7 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM C. 6.9 m/s D. 13.8 m/s E. 16.2 m/s Question 10 1 pts You drive down the road as rain drops fall straight down at a constant 8 m/s (due to air resistance) in the ground frame. From inside the car, the drops appear to fall at 60 degrees from the vertical direction. How fast do the drops appear to be moving when viewed from the car frame? A. 8 m/s B. 13.8 m/s C. 16.0 m/s D. 18 m/s E. 21.8 m/s Question 11 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 8 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM Rachel is pushing a box across a horizontal frictionless table with 10 N of force while Ross, at the same time, opposes her by pushing in the opposite direction with 15 N of force. Which of the following statements must be true? A. The box is moving in the direction that Rachel is pushing. B. The box is moving in the direction that Ross is pushing. C. The box is not moving. D. The box has constant velocity. E. None of these statements must be true. Question 12 1 pts A block sits on an adjustable ramp at some angle above the horizontal. The ramp and block surfaces have sufficient friction that the block does not slide. At what ramp angle does the normal force on the block equal half of its weight? A. 0 degrees B. 30 degrees C. 45 degrees D. 60 degrees E. 90 degrees https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 9 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM Question 13 1 pts In a lab experiment, a frictionless cart of mass M on a flat table is connected by a string over a pulley to a hanging mass consisting of several removable disks that have a total mass m. The cart is released from rest and its acceleration is measured. You then move one of the disks from the hanger to the cart and repeat the acceleration measurement. You do this several times. The final task of the lab is to make a plot of the cart’s acceleration versus hanging mass. What does the resulting plot look like? A. A B. B C. C D. D E. None of these plots can reasonably represent this relationship. Question 14 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 10 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM A 10 kg block sits on a frictionless table. A 2 kg block is held against it as shown and released. The coefficient of static friction between the blocks, , is 0.5. Which of the following conditions would allow the 2 kg block to remain in its position against the 10 kg block as shown? A. If the 10 kg block is motionless. B. If the 10 kg block is moving right at some minimum constant velocity. C. If the 10 kg block is moving right at some minimum constant acceleration. D. There is no condition where the 2 kg block won’t fall. Question 15 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 11 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM A 10 kg block sits on a frictionless table. A 2 kg block is held against it as shown and released. The coefficient of static friction between the blocks, , is 0.5. How hard must the 10 kg box be pushed across a frictionless floor (to the right) so that the 2 kg box will not slide down the front face of the 10 kg box when released? A. With at least 39 N. B. With at least 54 N. C. With at least 78 N. D. With at least 157 N. E. With at least 235 N. Question 16 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 12 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM In the diagram shown three masses (50, 10, and 200 kg) are connected by two different strings draped over pulleys. The middle 10 kg mass slides on a frictionless table. Which string has greater tension? A. Left B. Right C. They have the same tension. Question 17 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 13 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM In the diagram shown three masses (50, 10, and 200 kg) are connected by two different strings draped over pulleys. The middle 10 kg mass slides on a frictionless table. What is the tension in the right string? A. 490 N B. 773 N C. 830 N D. 1960 N Question 18 1 pts Who experiences a larger centripetal acceleration due to the Earth’s rotation: person A who is standing on the equator or person B who at the same time is standing halfway between the equator and the north pole? A. Person A https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 14 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM B. Person B C. They experience the same radial acceleration. D. It depends on the mass of each person. Question 19 1 pts A simple pendulum with a string length of 0.5 m and mass of 2 kg oscillates at its natural frequency. When the mass is directly under the pivot point, the mass moves at 0.44 m/s. What is the tension in the string at that point? A. 0.0 N B. 0.39 N C. 0.77 N D. 19.62 N E. 20.37 N https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 15 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM Question 20 1 pts You are driving a 1200 kg sports car on a flat road. Ahead you see a circular hill with radius 20 m, followed by a circular dip with radius 20 m. You decide to have some fun. You want to go over the hill so fast that your tires barely remain in contact with the road when you are at the top of the hill. How fast do you need to go at that point? A. 9.9 m/s B. 14 m/s C. 19.8 m/s D. 196 m/s E. This is not possible. Question 21 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 16 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM You are driving a 1200 kg sports car on a flat road. Ahead you see a circular hill with radius 20 m, followed by a circular dip with radius 20 m. You decide to have some fun. You want to feel "two g's" at the bottom of the dip. This means the car must push up on you with a force equal to twice your weight. How fast do you need to go at the bottom to make this happen? A. 9.9 m/s B. 14 m/s C. 19.8 m/s D. 196 m/s E. This is not possible. Question 22 1 pts https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 17 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM The masses and radii of the Earth and the Mars are given below. ME = 6.0 x 1024 kg RE = 6.4 x 106 m MM = 6.4 x 1023 kg RM = 3.4 x 106 m What is the relationship between the magnitudes of the gravitational forces they apply to each other? A. Fon Mars = 82.2 Fon Earth B. Fon Mars = 12.5 Fon Earth C. Fon Mars = 3.5 Fon Earth D. Fon Mars = 1.0 Fon Earth E. Fon Mars = 0.04 Fon Earth Question 23 1 pts Two planets orbit the same star. Planet 1 has an orbital radius R. Planet 2 has an orbital radius four times larger. By what factor do the two planets’ periods T1 and T2 relate? A. T1 is twice T2 B. T2 is twice T1 https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 18 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM C. T1 is four times T2 D. T2 is four times T1 E. T1 is eight times T2 F. T2 is eight times T1 Question 24 1 pts Knowing that surface gravity on the moon is about one sixth that on earth and that the moon is roughly 100 times less massive, what is a good estimate of the moon’s radius? A. 0.06 times the Earth’s radius B. 0.24 times the Earth’s radius C. 0.002 times the Earth’s radius D. 0.04 times the Earth’s radius E. 0.94 times the Earth’s radius Question 25 1 pts What is your favorite class this semester? PHYS 125 https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 19 of 20 Quiz: PHYS 125, Exam 1, Fall 2020 8/30/23, 2:31 PM No new data to save. Last checked at 2:30pm Submit Quiz https://canvas.rice.edu/courses/32915/quizzes/43571/take?preview=1 Page 20 of 20