Question Detail

PHY 101 Rigid Body Dynamics Objective Question

Question

For a rigid body rotating with angular frequency ω, the total kinetic energy is the sum of the kinetic energies of its constituent particles. This sum can be expressed as Σ (1/2) m_i v_i². What is the correct simplification of this expression using angular velocity?
Options
A Σ (1/2) m_i ω r_i
B Σ (1/2) m_i ω² r_i
C Σ (1/2) m_i ω² r_i²
Correct Answer
D Σ (1/2) m_i ω r_i²
Correct Answer

Option C is the correct answer.

Detailed Explanation

For a rigid body rotating with angular frequency ω, the linear speed of a particle i at a distance r_i from the axis is v_i = ω r_i. Substituting this into the kinetic energy expression gives KE = Σ (1/2) m_i (ω r_i)² = Σ (1/2) m_i ω² r_i².

Hint

Relate the linear velocity of a particle in a rotating rigid body to its angular velocity and distance from the axis.

Question Info