ROTATIONAL MOTION

What is the significance of the cross product in the torque expression τ = rᵢ × mᵢg?

• It calculates linear momentum
• It gives the scalar mass
• It measures speed
• It accounts for the direction and perpendicular distance in torque

What type of equilibrium is achieved when a body is balanced at its centre of gravity?

• Dynamic equilibrium
• Thermal equilibrium
• Chemical equilibrium
• Mechanical equilibrium

Under what condition does the centre of gravity coincide with the centre of mass?

• Only in symmetric bodies
• In zero gravity
• In non-uniform gravitational field
• In uniform gravitational field

What does the equation Σ mᵢrᵢ = 0 imply about the origin when rᵢ is measured from it?

• The origin is the geometric center
• The origin is the point of suspension
• The origin is the centre of mass
• The origin is arbitrary

Why can g be taken out of the summation in the torque equation Σ rᵢ × mᵢg?

• Because g is zero
• Because g varies with height
• Because g is scalar
• Because g is constant for all particles in uniform gravity