Three point masses are fixed at distances ,

PHYSICS · Single correct · AP · Physics 1: Algebra-based · Torque and Rotational Dynamics · Torque and Rotational Dynamics

Problem

Three point masses are fixed at distances

a

2a

, and

3a

from a common axis. Their respective masses are

2m

m

, and

3m

. Which of the following gives the total rotational inertia

I

of the system about the axis? (a)

I=\dfrac{1}{2}\left[2m a^{2}+m(2a)^{2}+3m(3a)^{2}\right]

(b)

I=2m a^{2}+m(2a)^{2}+3m(3a^{2})

(c)

I=2m a^{2}+m(2a)^{2}+3m(3a)^{2}

(d)

I=(2m+m+3m)\left(\dfrac{a+2a+3a}{3}\right)^{2}