ROTATIONAL MOTION

If a system's center of mass is at rest, can the system have kinetic energy?

• No, never
• Yes, only in space
• Yes, if parts are moving
• Only if rotating

A uniform wire is bent into an equilateral triangle. Where is its center of mass?

• At a vertex
• At the midpoint of a side
• At the circumcenter
• At the centroid of the triangle

A disc has a hole cut out from one side. Where is the center of mass now?

• Still at the center
• Shifted toward the hole
• Shifted away from the hole
• It disappears

Which of the following systems has its center of mass at the origin if masses are symmetrically placed?

• Two equal masses at (a,0) and (a,0)
• Two equal masses at (a,0) and (-a,0)
• One mass at (a,0)
• Two unequal masses at (a,0) and (-a,0)

If the center of mass of a system is accelerating, what can be concluded?

• No external force is acting
• Only internal forces are present
• A net external force is acting on the system
• The system is at rest