Problem 7, Page 226

What is the net torque about the axle on the pulley in the figure?

Problem 16, Page 227

Three identical coins lie on three corners of a square 10.0 cm on a side. Determine the coördinates of the centre of gravity of the system of three coins.

Problem 23, Page 227

Two thin beams are joined end-to-end as shown in the figure to form a single object. The left beam has mass 10.0 kg and has length 1.00 m, and the right beam has mass 40.0 kg and length 2.00 m.

1. How far from the left end is the centre of gravity?
2. What is the gravitational torque on the object about a horizontal axis through its left end?

Problem 2, Page 226

A computer hard disk starts from rest, then speeds up with an angular acceleration of 190 rad/s² until it reaches its final angular speed of 7200 rpm. How many revolutions has the disk made 10.0 s after it starts up?

Problem 33, Page 228

While sitting in a swivel chair, you push against the floor with your heel to make the chair spin. The 7.0 N frictional force is applied at a point 40 cm from the chair's rotation axis, in the direction tha tcauses the greates angular acceleration. If that angular acceleration is 1.8 rad/s², what is the total moment of inertia about the axis of you and the chair?

Problem 35, Page 228

A 200-g, 20-cm-diameter plastic disk is spun on the axle through its centre by an electric motor. What torque must the motor supply to take the disk from 0 to 1800 rpm in 4.0 s?

Problem 37, Page 228

A frictionless pulley, which can be modelled as a 0.80-kg solid disk with a 0.30-m radius, has a rope going over it, as shown in the figure. The tension in the rope is 10 N on one side and 12 N on the other side. Determine the angular acceleration of the pulley.

Problem 41, Page 228

A 1.5-kg block and a 2.5-kg block are attached to opposite ends of a light rope. The rope hangs over a solid, frictionless pulley that is 30 cm in diameter and has a mass of 0.75 kg. When the blocks are released, what is the acceleration of the lighter block?