2. A person is standing on a rotating platform with hands at his side. The rotation rate of the platform is 0.90 rev/s. The person then raises his arms to a horizontal position and the rotation rate decreases to 0.60 rev/s. Why does the rotation rate change? By what factor has the moment of inertia changed?

9. A figure skater with outstretched arms spins with an initial rotation rate of 1.0 rev every 1.2 s. She can increase her rotation speed by bringing her arms close to her body. Suppose her final rotation rate is 3.0 rev every 1.2 s. Find her moment of inertia with her arms close to her body if her moment of inertia with outstretched arms is 5.0 kg-m?. (Answer: I = 1.7 kg · m²)

4. A skater has a moment of inertia of 105.0 kg.m² when his arms are outstretched and a moment of inertia of 64.0 kg.m² when his arms are tucked in close to his chest. If he starts to spin at an angular speed of 80.0 rpm (revolutions per minute) with his arms outstretched, what will his angular speed be when they are tucked in? rpm

Jimmothy has a flywheel. It rotates about its central axis. It starts from rest and accelerates uniformly. After completing 100 revolutions, the flywheel reaches an angular speed of 70.9 rad/s. It's your job to calculate the following: 1. What is The angular acceleration of the flywheel 2. What is The time required to complete the first 50 revolutions. 3. What is The time required to complete the second 50 revolutions.

A dentist's drill starts from rest. After 3.50 s of constant angular acceleration it turns at a rate of 2.30 x 104 rev/min. (a) Find the drill's angular acceleration. rad/s2 (b) Determine the angle (in radians) through which the drill rotates during this period. rad

A merry-go-round rotates from rest with an angular acceleration of 1.88 rad/s?. How long does it take to rotate through (a) the first 3.24 rev and (b) the next 3.24 rev? (a) Number i Units (b) Number i Units

A 85.0-kg skater begins a spin with an angular speed of 8.00 rad/s. By changing the position of her arms, the skater decreases her moment of inertia to one-fourth its initial value. What is the skater's final angular speed? my final answer is 16 rad/s? I'm not sure if it's correct because on test it was marked as incorrect. Can you please explain why it's incorrect?

3. The cord, which is wrapped around the disk, is given an acceleration of a = (10t) m/s, where t is in seconds. Starting from rest, determine the angular displacement, angular velocity, and angular acceleration of the disk when t = 5 s. a = (10t) m/s² 0.5 m

A wheel is rotating at an angular speed of 2.0 radians. How much torque is needed to accelerate it to 4.0 radians/s in 5 s? The wheel has a moment of inertia of 0.25 kg.m² A. 0.01 m.N B. 0.10 m.N C. 1.0 m.N D. 10 m.N