AP Physics 1 5.6: Newton’s Second Law in Rotation

Relate changes in angular velocity to net torque and rotational inertia using Newton’s second law in rotational form for a rigid system.

Exam points

Use net torque and rotational inertia to determine the angular acceleration of a rigid system.
Explain that angular acceleration follows the direction of the net torque about the selected axis.

Covered syllabus points

5.6.A—Describe the conditions under which a system’s angular velocity changes

[Maximum number: 2]

(12 points, suggested time 25 minutes)
The left end of a uniform beam of mass M and length L is attached to a wall by a hinge, as shown in Figure 1. One end of a string with negligible mass is attached to the right end of the beam. The other end of the string is attached to the wall above the hinge at Point 1. The beam remains horizontal. The hinge exerts a force on the beam of magnitude $F_{\mathrm{H}}$ , and the angle between the beam and the string is $\theta=\theta_{1}$ .

The string is cut, and the beam begins to rotate about the hinge with negligible friction. On the following axes, sketch the angular speed of the beam as a function of time for the time interval while the beam falls but before the beam becomes vertical.

Figure for Question 5.6 Newton’s Second Law in Rotational Form question 1 — AP Physics 1: Algebra-Based

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Covered syllabus points

5.6 Newton’s Second Law in Rotational Form question 1