QuickCheck 12.1 Two coins rotate on a turntable. Coin B is twice as far from the axis as coin A. The angular velocity of A is twice that of B. The angular velocity of A equals that of B. The angular velocity of A is half that of B. 2

QuickCheck 12.1 Two coins rotate on a turntable. Coin B is twice as far from the axis as coin A. The angular velocity of A is twice that of B. The angular velocity of A equals that of B. The angular velocity of A is half that of B. 3

QuickCheck 12.2 The fan blade is speeding up. What are the signs of ω and α? ω is positive and α is positive. ω is positive and α is negative. ω is negative and α is positive. ω is negative and α is negative. 4

QuickCheck 12.2 The fan blade is speeding up. What are the signs of ω and α? ω is positive and α is positive. ω is positive and α is negative. ω is negative and α is positive. ω is negative and α is negative. 5

QuickCheck 12.3 A baseball bat is cut in half at its center of mass. Which end is heavier? The handle end (left end) The hitting end (right end) The two ends weigh the same. 6

QuickCheck 12.3 A baseball bat is cut in half at its center of mass. Which end is heavier? The handle end (left end) The hitting end (right end) The two ends weigh the same. 7

QuickCheck 12.4 Dumbbell A. Dumbbell B. Which dumbbell has the larger moment of inertia about the midpoint of the rod? The connecting rod is massless. Dumbbell A. Dumbbell B. Their moments of inertia are the same. 8

QuickCheck 12.4 Dumbbell A. Dumbbell B. Which dumbbell has the larger moment of inertia about the midpoint of the rod? The connecting rod is massless. Dumbbell A. Dumbbell B. Their moments of inertia are the same. Distance from the axis is more important than mass. 9

QuickCheck 12.5 The four forces shown have the same strength. Which force would be most effective in opening the door? Force F1 Force F2 Force F3 Force F4 Either F1 or F3 10

QuickCheck 12.5 The four forces shown have the same strength. Which force would be most effective in opening the door? Force F1 Force F2 Force F3 Force F4 Either F1 or F3 Your intuition likely led you to choose F1. The reason is that F1 exerts the largest torque about the hinge. 11

QuickCheck 12.6 Which third force on the wheel, applied at point P, will make the net torque zero? 12

QuickCheck 12.6 Which third force on the wheel, applied at point P, will make the net torque zero? 13

QuickCheck 12.7 A student gives a quick push to a puck that can rotate in a horizontal circle on a frictionless table. After the push has ended, the puck’s angular speed Steadily increases. Increases for awhile, then holds steady. Holds steady. Decreases for awhile, then holds steady. Steadily decreases. 14

QuickCheck 12.7 A student gives a quick push to a puck that can rotate in a horizontal circle on a frictionless table. After the push has ended, the puck’s angular speed Steadily increases. Increases for awhile, then holds steady. Holds steady. Decreases for awhile, then holds steady. Steadily decreases. A torque changes the angular velocity. With no torque, the angular velocity stays the same. This is Newton’s first law for rotation. 15

QuickCheck 12.8 Which object is in static equilibrium? 16

QuickCheck 12.8 Which object is in static equilibrium? 17

QuickCheck 12.9 What does the scale read? 500 N 1000 N 2000 N 4000 N Answering this requires reasoning, not calculating. 18

QuickCheck 12.9 What does the scale read? 1000 N 2000 N 4000 N 500 N 19

QuickCheck 12.10 A wheel rolls without slipping. Which is the correct velocity vector for point P on the wheel? 20

QuickCheck 12.10 A wheel rolls without slipping. Which is the correct velocity vector for point P on the wheel? 21

QuickCheck 12.11 Two buckets spin around in a horizontal circle on frictionless bearings. Suddenly, it starts to rain. As a result, The buckets speed up because the potential energy of the rain is transformed into kinetic energy. The buckets continue to rotate at constant angular velocity because the rain is falling vertically while the buckets move in a horizontal plane. The buckets slow down because the angular momentum of the bucket + rain system is conserved. The buckets continue to rotate at constant angular velocity because the total mechanical energy of the bucket + rain system is conserved. None of the above. 22

QuickCheck 12.11 Two buckets spin around in a horizontal circle on frictionless bearings. Suddenly, it starts to rain. As a result, The buckets speed up because the potential energy of the rain is transformed into kinetic energy. The buckets continue to rotate at constant angular velocity because the rain is falling vertically while the buckets move in a horizontal plane. The buckets slow down because the angular momentum of the bucket + rain system is conserved. The buckets continue to rotate at constant angular velocity because the total mechanical energy of the bucket + rain system is conserved. None of the above. 23