Lesson: Newton’s Second Law of Motion for Rotation in terms of Moment of Inertia and Angular Acceleration Physics • 9th Grade

In this lesson, we will learn how to calculate the torque on an object given its moment of inertia and its angular acceleration

Lesson Plan

Students will be able to

use to find the torque on an object given its moment of inertia and its angular acceleration,
determine the moment of inertia of an object from a graph of its angular acceleration against the torque applied to it.

Lesson Video

Lesson Worksheet

Q1:

A solid copper disk has a mass of 10 kg, a radius of 12 cm, and a thickness of 2.5 cm. The disk is initially not rotating. What torque must be applied to the disk, about the axis around which the disk is rotationally symmetric, to produce an angular acceleration of 0.25 rad/s²?

Q2:

The graph shows how the angular accelerations of five objects, i–v, vary with the torque applied to them.

Which object has the greatest moment of inertia?

Which object has the smallest moment of inertia?

Q3:

An object that is initially not rotating has a constant torque of 3.6 N⋅m applied to it. The object has a moment of inertia of 6 kg⋅m². What is the magnitude of the angular acceleration of the object?