Question

Which are true

1. a rigid body undergoing planar motion is pinned at the center of mass in the plane of motion; all non-CM points on the rigid body have the same angular velocity.

2. When a rigid body undergoes planar motion the body center of mass remains in a singular plane.

3. The normal force is never perpendicular to the surfaces that applies the normal force.

4. Mass moment of inertia of a rigid body indicates the magnitude of effort required to speed or slow down the rigid body.  

Answer 1

1. false

planar motion is a motion parallel to plane . it can be rotation translation or both. centre of mass also maybe moving

2. true . not just centre of mass ,plane followed by each point remains unchanged

3.true (in the case of rotation),torque = moment of inertia x angular acceleration

troque is the effort to change angular speed