ROTATIONAL MOTION

If all particles in a system have the same mass, how is the X-coordinate of centre of mass simplified?

• X = ∑xi
• X = (∑xi)/n
• X = n/(∑xi)
• X = m∑xi

What is the centre of mass of a system with two particles of masses 2 kg and 3 kg located at x = 1 m and x = 4 m respectively?

• 2.5 m
• 2.8 m
• 3.0 m
• 3.2 m

How does the centre of mass behave under uniform gravitational field?

• It remains stationary
• It moves randomly
• It moves as if all mass is concentrated there
• It disappears

What is the unit of the centre of mass coordinate X?

• Kilograms
• Same as that of position (e.g., meters)
• Dimensionless
• Meters per second

Why is the vector form of the centre of mass equation more economical?

• It eliminates mass
• It is easier to integrate
• It combines three scalar equations into one
• It reduces dimensionality