BYU-Idaho Principles of Physics Exam 2 PDF

Pri n ci pl es o f Ph y si c s Exam 2 Document 1. I understand that I have agreed to follow the Honor Code to be able to receive the blessings of gaining an education while I am a student at BYU-Idaho. I will not cheat or do anything that would cause me...

Pri n ci pl es o f Ph y si c s Exam 2 Document 1. I understand that I have agreed to follow the Honor Code to be able to receive the blessings of gaining an education while I am a student at BYU-Idaho. I will not cheat or do anything that would cause me to be dishonest in any way. a. I agree b. I disagree The multiple choice problems are each worth 3 points, 2 points for the answer and 1 for the explanation and/or work. All other problems are worth the points noted, with 2 points for the answer and the rest for the work. 2. Joe and Bill are playing tug-o-war. Joe is pulling with a force of 200 N. Bill is simply hanging onto the rope. Neither person is moving. What is the tension of the rope? a. 400 N b. 300 N c. 0N d. 200 N 3. An object is moving to the right in a straight line. The net force acting on the object is also directed to the right, but the magnitude of the force is decreasing with time. The object will a. continue to move to the right, with its speed decreasing with time. b. continue to move to the right with a constant speed. c. continue to move to the right, with its speed increasing with time. d. stop and then begin moving to the left. 4. Two unequal masses M and m are connected by a light cord passing over a pulley of negligible mass. When released, the system accelerates. Friction is negligible. Which figure below gives the correct free-body force diagrams for the two masses in this moving system? a. b. c. d. Use this graph for the next two questions. 5. At the 2-meter position, what is the direction of the force? a. In the positive direction (to the right) b. In the negative direction (to the left) c. There is no force at this point. 6. At which meter-mark is there most nearly a stable equilibrium point in the potential energy graph? a. 1 b. 2 c. 3 d. 4 e. 5 f. 6 7. The force a spring exerts on a body is a conservative force because a. a spring always exerts a force opposite to the displacement of the body. b. a spring always exerts a force parallel to the displacement of the body. c. the work a spring does on a body is equal for compressions and extensions of equal magnitude. d. the work a spring does on a body is equal and opposite for compressions and extensions of equal magnitude. e. the net work a spring does on a body is zero when the body returns to its initial position. 8. A large truck collides head-on with a cyclist. During the collision, a. the truck exerts a smaller amount of force on the cyclist than the cyclist exerts on the truck. b. the truck exerts a greater amount of force on the cyclist than the cyclist exerts on the truck. c. the truck exerts the same amount of force on the cyclist as the cyclist exerts on the truck. d. the truck exerts a force on the cyclist, but the cyclist exerts no force onto the truck. 9. A string is attached to the rear-view mirror of a car. A ball is hanging on the other end of the string. The car is driving around in a circle at a constant speed. Which of the following lists gives all of the forces directly acting on the ball? a. tension, gravity, and the centripetal force b. tension, gravity, the centripetal force, and friction c. tension d. tension and gravity --------------------------------------------------------------------------------------------------------------------- 10. A skydiver reaches a “terminal velocity” of 120.0 km/h. If the skydiver has a mass of 59.0 kg, what is the magnitude of the upward force on the skydiver due to wind resistance? (5 points) 11. A 65 kg ice skater pushes off his partner and accelerates backwards at 1.3 m/s2. If the partner accelerates in the opposite direction at 2.0 m/s2, what is the mass of the other skater? Assume that frictional forces are negligible. (5 points) 12. Engineers are designing a curved section of a highway. If the radius of curvature of the curve is 194 m, at what angle should the curve be banked so that a car traveling at 29.0 m/s will stay on the road without the aid of frictional forces? (6 points) 13. In an amusement park ride, passengers stand inside an 8.0 m radius cylinder. Initially the cylinder rotates with its axis oriented along the vertical. After the cylinder has acquired sufficient speed, it tilts into a vertical plane, that is, the axis tilts into the horizontal, as shown in the figure. Suppose that, once the axis has tilted into the horizontal, the ring rotates once every 4.5 s. If a rider’s mass is 70.0 kg, with how much force does the ring push on her at the top of the ride? (7 points) ------------------------------------------------------------------------------------------------------------------- The figure shows a block of mass m resting on a 20.0° slope. The block has coefficients of friction µ s = 0.55 and µk = 0.45 with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg. 14. What is the minimum mass m that will stick and not slip? (7 points) 15. What is the acceleration of the hanging mass if the mass m=1.9 kg? (6 points) 16. If m=1.9 kg and the hanging mass starts 0.54 m above the ground, what is the speed of the hanging mass when it hits the ground? (4 points) 17. Continuing where 16. left off, if m=1.9 kg, how long (time) after the hanging mass hits the ground does the mass m slide up the slope before stopping? (6 points) -------------------------------------------------------------------------------------------------------------------- A tetherball is on a 2.1 m string which makes an angle of 44° with the vertical as it moves around the pole in a horizontal plane. The mass of the ball is 1.3 kg. 18. What is the ball’s speed? (8 points) 19. How long does it take the ball to make one revolution? (4 points) ----------------------------------------------------------------------------------------------------------------- You want to build a sculpture that incorporates the ideas you’ve learned in your physics class to go in your entryway. A marble (mass=4.9g) is shot up a tube by a spring (k=20.0N/m) to the top of a roller coaster. Water flows through the tube so it is frictionless. All heights are measured from the top of the compressed spring. A C 33.0cm B 25.0cm green spring 10.0cm 20. How much must the spring be compressed for the marble to have a speed of 1.3m/s at the top of the hump (point C)? (6 points) 21. The ball is spit out onto a green at the end of the roller coaster. If it travels 37.5cm on the green with a friction coefficient of 0.888, how much work was done on the ball by friction? (6 points) 22. What is the force of friction acting on the ball while on the green? (4 points)