ROTATIONAL MOTION

How does the centre of mass move when no external force acts on the system?

• Accelerates
• With constant velocity
• Remains at rest
• Oscillates

What is the vector equation that defines the centre of mass?

• R = ∑mi ri
• R = (∑mi ri)/M
• R = ∑ri/M
• R = M/(∑mi ri)

Why can't we perform actual summations for centre of mass of a rigid body?

• Masses are unknown
• Particles are not discrete
• Number of particles is too large
• Coordinates are complex

What is the centre of mass of a system with particles at (0,0), (2,0), and (0,2) with equal masses?

• (1,1)
• (2/3, 2/3)
• (0,0)
• (2,2)

How is the X-coordinate of centre of mass affected if all xi are increased by a constant?

• X remains same
• X increases by the same constant
• X doubles
• X becomes zero