Phy rotational dynamics

Question 1

Lever arm

Answer 1

Lever arm is the perpendicular distance from an axis to the line of action of the force.

Question 2

Mechanical equilibrium

Answer 2

An object in mechanical equilibrium must satisfy the following conditions:
*The net external force must be zero
*The net external torque must be zero

Question 3

Centre of gravity

Answer 3

The centre of gravity of a homogeneous symmetric body, must lies on the axis of symmetry.