Name: Class: Date: Exam 4--PHYS 101--F14 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A wheel, initially at rest, rotates with a constant acceleration of 2.0 rad/s 2. What is the time interval required for it to reach a 16-rad displacement after starting from rest? a. 16 s b. 4.0 s c. 8.0 s d. 2.8 s 2. A potter's wheel moves from rest to an angular speed of 8.0 rev/s in 2.0 s. Find its angular acceleration in rev/s 2. a. 16 rev/s 2 b. 8.0 rev/s 2 c. 4 rev/s 2 d. 0.25 rev/s 2 3. Which of these is a measure of angular displacement? I. radians II. degrees III. revolutions IV. arcs a. I alone b. I & II c. I, II, and III d. III & IV 4. One revolution is the same as a. 57 rad π b. 2 rad c. π rad d. 1 rad e. 2π rad 5. What is the angular velocity of the second hand of a clock? a. 1 rad/s b. 2 rad/s c. 0.5 rad/s d. 0.1 rad/s 6. If a wheel turns with constant angular speed then: a. the angle through which the wheel turns in each second increases as time goes on b. the angle through which the wheel turns in each second decreases as time goes on c. each point on its rim moves with constant acceleration d. the wheel turns through equal angles in equal times e. each point on its rim moves with constant velocity 7. An object at rest begins to rotate with a constant angular acceleration. If this object has an angular velocity of ω in time t, what is its angular velocity after time 1 2 t? a. 0 b. 2ω c. ω/4 d. 4ω e. ω/2 1
8. A particle moves in a circular path of radius 0.10 m with a constant angular speed of 5 rev/s. The acceleration of the particle is: 12. The following figure shows a configuration of particles arranged on an equilateral triangle, whose sides are all 4.0 m. The rotation axis is the dashed line in this figure. What is the moment of inertia for this configuration of particles? a. 500π m/s 2 b. 1000π 2 m/s 2 c. 0.10π m/s 2 d. 0.5 m/s 2 e. 10π 2 m/s 2 9. What is the moment of inertia for a hula-hoop with a mass of 1kg and a diameter of 1m? a. 0.25 kgm² b. 0.50 kgm² c. 2 kgm² d. 1 kgm² 10. A 1 500-kg car rounds an unbanked curve with a radius of 52 m at a speed of 12 m/s. What minimum coefficient of friction must exist between the road and tires to prevent the car from slipping? a. 48 kg m 2 b. 72 kg m 2 c. 96 kg m 2 d. 24 kg m 2 13. Consider this figure of a rod rotating about the axis labeled C. What is the net torque? a. 0.18 b. 0.30 c. 0.28 d. 0.37 11. Consider this bar that can rotate about points A, B, and C. About which point, does the bar exhibit the greater moment of inertia? a. 30 Nm counter clockwise b. 0 Nm c. 40 Nm counter clockwise d. 60 Nm counter clockwise 14. Consider the rod in the previous question. The rod has a mass of 3 kg. After 2 seconds of the torque acting on the rod, what is the rod s angular velocity? a. A b. B c. C d. A & C e. they are all the same moment of inertia a. 30 rad/s b. 60 rad/s c. 45 rad/s d. 15 rad/s 2
15. A bar has a moment of inertia of 2 kg m 2 and is rotating at 3 rev/s. It engages with a flywheel, which is stationary and has a moment of inertia of 4 kg m 2. After they engage, both move at the same speed. What is this new speed? 19. This figure shows a hydraulic lift. The force F 1 has a magnitude of 100 N, and the area A 1 is 0.01 m 2. If the area A 2 is 1.0 m 2, what is the weight of the truck? a. 1 rev/s b. 1.5 rev/s c. 3 rev/s d. 9 rev/s e. 4.5 rev/s 16. A figure skater is rotating at 5 rev/s. Then, she moves her arms out and is then rotating at 10 rev/s. Which of these statements is true? a. she has increased her moment of inertia by a factor of 2 b. she has decreased her moment of inertia by a factor of 2 c. her moment of inertia is the same; she has just sped up d. she has increased her moment of inertia by a factor of 4 e. she has decreased her moment of inertia by a factor of 4 17. Which of these is considered a fluid: I. Solid II. Liquid III. Gas a. II only b. I, II, and III c. II & III d. III only 18. How many cubic meters of water are in 300 kg of water? a. 100,000 N b. 10,000 N c. 1,000,000 N d. 1000 N 20. Pascal s principle says: a. the buoyant force equals the weight of the displaced fluid b. a change in pressure at one point in an incompressible fluid is felt at every other point in the fluid c. energy is conserved in a flowing ideal fluid d. a small input force always causes a large output force 21. A tendon in your arm, without any pressure on it, has a length of 0.10 m. The cross sectional area is 0.75 cm 2 (=7.5 10-5 m 2 ) By how much does it stretch (in cm) when a force of 100 N is applied to it? (The Young s modulus for a tendon is 2 10 7 Pa) a. 0.3 m 3 b. 3 m 3 c. 30 m 3 d. 300 m 3 e. 3000 m 3 a. 7.5 cm b. 0.7 cm c. 0.4 cm d. 1.3 cm 3
22. This figure shows a barometer. If the barometer is filled with water, what is the height when the pressure P=0.2 atmosphere? 26. Consider this manometer. Which statement best describes the relationship between P and P 0? a. 760 mm b. 17 m c. 2.0 m d. 10 m 23. A blood platelet drifts along with the flow of blood through an artery that is partially blocked. As the platelet moves from the wide region into the narrow region, the blood pressure: a. increases b. decreases c. stays the same 24. The continuity equation is based on which of these laws: a. Conservation of Energy b. Archimede s Law c. Conservation of Matter d. Conservation of Continuity a. P>P 0 b. P=P 0 c. P<P 0 d. it depends on the density of the material in the manometer 27. Water flows through a pipe at 3.0 m/s with a cross-sectional area of 0.5 m 2. The pipe grows wider to 1.0 m 2. What is the speed of the water in the larger pipe? a. 6.0 m/s b. 1.0 m/s c. 1.5 m/s d. 3.0 m/s 25. A ping-pong ball has an average density of 84.0 kg/m 3 and a volume of 3.0x10-5 m 3. If the ball is completely submerged in water, what is the buoyant force acting on it? a. 3 N b. 0.03 N c. 30 N d. 0.3 N 4
ID: A Exam 4--PHYS 101--F14 Answer Section MULTIPLE CHOICE 1. ANS: B PTS: 1 DIF: 2 TOP: 7.2 Rotational Motion Under Constant Angular Acceleration 2. ANS: C PTS: 1 3. ANS: C PTS: 1 4. ANS: E PTS: 1 5. ANS: D PTS: 1 6. ANS: D PTS: 1 7. ANS: E PTS: 1 8. ANS: E PTS: 1 9. ANS: A PTS: 1 10. ANS: C PTS: 1 DIF: 2 REF: F14 TOP: 7.4 Centripetal Acceleration 11. ANS: A PTS: 1 12. ANS: C PTS: 1 13. ANS: A PTS: 1 14. ANS: D PTS: 1 15. ANS: A PTS: 1 16. ANS: B PTS: 1 17. ANS: C PTS: 1 18. ANS: A PTS: 1 19. ANS: B PTS: 1 20. ANS: B PTS: 1 21. ANS: B PTS: 1 22. ANS: C PTS: 1 23. ANS: B PTS: 1 24. ANS: C PTS: 1 DIF: 2 TOP: 9.7 Fluids in Motion 9.8 Other Applications of Fluid Dynamics 25. ANS: D PTS: 1 26. ANS: C PTS: 1 27. ANS: C PTS: 1 1