Rotational Motion – Key Clicker Concepts

Eight question-and-answer style flashcards covering rotational inertia, rolling motion, torque, seesaw balance, centripetal forces, and angular momentum.

When is an object’s rotational inertia the greatest?

When most of its mass is located far away from the rotational axis.

For round objects rolling down an incline, what characteristic makes one roll fastest?

Having the lowest rotational inertia compared with its mass.

Which round object rolls down an incline fastest: a disk, a hoop, or a solid ball?

A solid ball rolls fastest because it has the smallest rotational inertia relative to its mass.

What is the definition of torque in rotational dynamics?

Torque equals a force multiplied by its lever arm (τ = F × r).

When two children of different weights balance on a seesaw, what can be said about the torques they produce?

They produce equal-magnitude torques in opposite directions.

In horizontal circular motion (e.g., whirling a tin can), what is the direction of the force that keeps the can moving in its circle?

The force (tension) on the can points inward toward the center of the circle (centripetal).

What is the direction of the force that the can exerts on the string while it is being whirled in a circle?

The can pulls outward on the string, opposite to the inward pull of the string on the can (Newton’s third law).

Write the basic formula for angular momentum of an object moving in a circle and state one way to double it.

Angular momentum L = m v r. Doubling any one of the variables—mass (m), linear speed (v), or radius (r)—will double the angular momentum if the others remain constant.