Author Question: A 1.20-kg ball is hanging on the end of a rope. The rope makes an angle 25.0 from the vertical when ... (Read 872 times)

Yi-Chen · **on:** Jul 29, 2018

A 1.20-kg ball is hanging on the end of a rope. The rope makes an angle 25.0 from the vertical when a 15.0 m/s horizontal wind blows. If the wind's force on the rope is negligible, what is the drag force on the ball?

A)

32.3 N

B)

24.1 N

C)

3.68 N

D)

5.49 N

E)

11.8 N

Question 2

A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her angular speed increases dramatically. The speed increase is a demonstration of

A)

conservation of kinetic energy: her moment of inertia is decreased, and so her angular speed must increase to conserve energy.
B)

conservation of total energy: her moment of inertia is decreased, and so her angular speed must increase to conserve energy.
C)

conservation of angular momentum: her moment of inertia is decreased, and so her angular speed must increase to conserve angular momentum.
D)

Newton's second law for rotational motion: she exerts a torque and so her angular speed increases.
E)

This has nothing to do with mechanics, it is simply a result of her natural ability to perform.