Two children weighing 60.0 kg and 45.0 kg,respectively,are sitting at different points on the edge of a rotating merry-go-round which has a radius of 4.0 m.What is the rotational inertia for the children?

Question

Quizplus · Accepted Answer

The formula for rotational inertia of a point mass is I = mr^2, where m is the mass of the object and r is the distance from the axis of rotation. Since both children are sitting on the edge of the merry-go-round, their distance from the axis of rotation is 4.0 m.

For child 1: 
I1 = (60.0 kg)(4.0 m)^2 = 960 kgm^2

For child 2: 
I2 = (45.0 kg)(4.0 m)^2 = 720 kgm^2

The total rotational inertia for the two children is the sum of their individual rotational inertia: 
I = I1 + I2 = 960 kgm^2 + 720 kgm^2 = 1680 kgm^2

Therefore, the correct option is C.

Two Children Weighing 60