Question

The conditions that the net external force and net external torque both vanish

	a.	must hold for a body in static equilibrium.
	b.	are satisfied only when the torque is computed about the center of mass.
	c.	must hold for every rigid body.
	d.	must hold whenever the net internal forces and torques vanish.

Two points are on a disk turning at a constant angular velocity about its center of mass. Point A is on the rim and point B is halfway between the rim and the rotation axis. Which of the statements below is FALSE?

	a	Point A moves a greater distance than point B in a time .
	b	Point A moves through a greater angle than point B in a time .
	c	Point A has a greater speed than point B.
	d	Point A has a greater linear acceleration than point B.

Answer 1

Part A) option 'a' is correct because if net external force and net external torque vanish it leads to the static equilibrium of the body.

Part B) option 'c' is correct. The speed of A should be greater than the speed of B because speed in angular motion is given by (V=W*R) where 'W' stands for angular speed and 'R' stand for distance from axis of rotation and in this case distance of A is greater than that of B because it is at the rim while B is at half way.