ame: Class: Date: Exam 2--PHYS 101-Fall 2009 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Consider this figure of a roller coaster: At which of these points is the speed of the car the greatest? a. A c. C b. B d. D 2. In the previous figure, the cart has a mass of 1000 kg, and, at point A, it is at rest. What is the speed of the cart at point D? a. 48 m/s d. 0 m/s b. 28 m/s e. 56 m/s c. 40 m/s 1
ame: 3. A man jumps off of a cliff 55 meters high. What is his speed when he gets to the bottom? a. 5.6 m/s c. 33 m/s b. 55 m/s d. Not enough information 4. You drop a ball from a certain height. Which of these statements describe the changes in gravitational potential and kinetic energy as the ball falls to the ground? (KE=kinetic energy, PE=gravitational potential energy) a. KE is decreasing and PE is increasing c. both PE and KE are decreasing b. KE is increasing and PE is decreasing d. both PE and KE are increasing 5. An outfielder throws a 0.150-kg baseball at a speed of 40.0 m/s and an initial angle of 30.0. What is the kinetic energy of the ball at the highest point of its motion? a. 120 J c. 90 J b. 60 J d. 30 J 6. Two stones, one twice the mass of the other, are dropped from a cliff. Just before hitting the ground, what is the kinetic energy of the heavy stone compared to the light one? a. quarter as much d. twice as much b. half as much e. four times as much c. the same 7. Which of these statements is true? a. both energy and momentum are scalar quantities b. both energy and momentum are vector quantities c. energy is a scalar quantity; momentum is a vector quantity d. energy is a vector quantity; momentum is a scalar quantity 2
ame: 8. A valid unit for momentum is which of the following? a. kg m/s 2 b. kg/m 2 c. kg m/s d. N m 9. Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s, and just after is 3.5 m/s. If the ball is in contact with the floor for 0.025 s, what is the magnitude of the average force applied by the floor on the ball? a. 133 N b. 3.5 N c. 60 N d. 3.0 N 10. If the momentum of an object is tripled, its kinetic energy will change by what factor? (Assume the mass of the object is unchanged.) a. nine b. three c. zero d. one-third 3
ame: 11. Ann the Astronaut weighs 60 kg. She is space walking outside the space shuttle and pushes a 350-kg satellite away from the shuttle at 0.90 m/s. What speed does this give Ann as she moves toward the shuttle? a. 5.3 m/s b. 9.0 m/s c. 8.5 m/s d. 4.0 m/s 12. A system of particles has a momentum of zero. Which of these statements is true about the kinetic energy of the system? a. the kinetic energy is zero c. the kinetic energy is negative b. the kinetic energy is positive d. there is not enough information 13. A bouncy rubber ball and bean bag, each with the same mass, fall to the floor from the same height. Which of these statements about the force imparted to the floor is true? a. the rubber ball imparts a greater force c. the ball and bean bag impart the same force b. the bean bag imparts a greater force d. there is not enough information 14. In elastic collisions a. only energy is conserved c. only momentum is conserved b. both energy and momentum are conserved d. none of these 4
ame: 15. A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s. What is the wheel's average angular acceleration? a. 9.6 rad/s 2 b. 0.33 rad/s 2 c. 4.8 rad/s 2 d. 1.6 rad/s 2 16. A fan blade, initially at rest, rotates with a constant acceleration of 0.025 rad/s 2. What is the time interval required for it to reach a 4.2-rad displacement after starting from rest? a. 2.0 s b. 18 s c. 1.8 s d. 16 s 5
ame: 17. Kaisa sits on the outer rim of a merry-go-round, and Chad sits midway between the rim and center. The merry-go-round makes 1 revolution every 2 seconds. Chad s angular velocity is... a. one-quarter of Kaisa s d. same as Kaisa s b. four times Kaisa s e. one-half of Kaisa s c. twice Kaisa s 18. A car rounds a curve on a flat road. The coefficient of static friction between the road and tires is 0.70. If the curve has a radius of 50. meters, what is the maximum safe speed at which the car can round the curve? a. 340 m/s c. 19 m/s b. 35 m/s d. 71 m/s 6
ame: 19. A ventilation fan has blades 0.25 m long rotating at 20 revolutions per minute (rev/min). What is the centripetal acceleration of a point on the outer tip of a blade? a. 0.87 m/s 2 b. 1.1 m/s 2 c. 0.55 m/s 2 d. 0.23 m/s 2 20. An object at rest begins to rotate with a constant angular acceleration. If this object rotates through an angle q in the time t, through what angle did it rotate in the time 1/2 t? a. 3 θ d. 2θ 4 b. 4θ e. c. 1 4 θ 1 2 θ 7
ame: 21. What is the net torque on this bar, which rotates about the point O? a. 19 N m in the clockwise direction d. 16 N m in the clockwise direction b. 52 N m in the counterclockwise direction e. 0 N m c. 28 N m in the clockwise direction 22. A bolt and nut are to be tightened to a torque of 15 N m. If the wrench is 25 centimeters long, what is the minimum force that must be applied to get the required torque? a. 3.8 N c. 380 N b. 0.6 N d. 60 N 8
ame: 23. This figure shows the human arm. The forearm rotates about the elbow (point O), and the biceps exerts a force on the ulna at 0.03 m from the elbow. The total length of the forearm and hand is 0.35 m. What force must the biceps exert in order for this arm to hold the bowling ball (whose weight is 50. N) steady (i.e. in equilibrium)? (Assume the bicep exerts a force that is perpendicular to the forearm.) a. 220 N c. 18 N b. 50 N d. 580 N 24. When a tape is played on a cassette deck, there is a tension in the tape that applies a torque to the supply reel. Assuming the tension remains constant during playback, how does this applied torque vary as the supply reel becomes empty? a. the torque decreases c. the torque increases b. the torque remains the same 25. Which of these are the basic SI units for torque? a. kg m c. kg m2 s s 2 b. kg m d. s 2 m 26. The answer to this question is B. Bubble B on your scantron. a. A c. C b. B 9
Exam 2--PHYS 101-Fall 2009 Answer Section MULTIPLE CHOICE 1. ANS: D PTS: 1 2. ANS: C PTS: 1 3. ANS: C PTS: 1 4. ANS: B PTS: 1 5. ANS: C PTS: 1 6. ANS: D PTS: 1 7. ANS: C PTS: 1 8. ANS: C PTS: 1 DIF: 1 TOP: 6.1 Momentum and Impulse 9. ANS: C PTS: 1 DIF: 2 TOP: 6.1 Momentum and Impulse 10. ANS: A PTS: 1 DIF: 1 TOP: 6.2 Conservation of Momentum 11. ANS: A PTS: 1 DIF: 2 TOP: 6.2 Conservation of Momentum 12. ANS: D PTS: 1 13. ANS: A PTS: 1 14. ANS: B PTS: 1 15. ANS: D PTS: 1 DIF: 1 TOP: 7.1 Angular Speed and Angular Acceleration 16. ANS: B PTS: 1 DIF: 2 TOP: 7.2 Rotational Motion Under Constant Angular Acceleration 17. ANS: D PTS: 1 18. ANS: C PTS: 1 19. ANS: B PTS: 1 DIF: 2 TOP: 7.4 Centripetal Acceleration 20. ANS: C PTS: 1 21. ANS: C PTS: 1 22. ANS: D PTS: 1 23. ANS: D PTS: 1 24. ANS: A PTS: 1 25. ANS: C PTS: 1 26. ANS: B PTS: 1 1