A long, thin uniform bar of mass is pivoted about its center. Two vertical forces act…

PHYSICS · Single correct · AP · Physics C: Mechanics · Torque and Rotational Dynamics · Torque and Rotational Dynamics

Problem

1.2\,\text{m}

long, thin uniform bar of mass

2.0\,\text{kg}

is pivoted about its center. Two vertical forces act on the bar simultaneously: • A

10\,\text{N}

upward force at the right end of the bar. • An

8\,\text{N}

downward force at a point

0.30\,\text{m}

to the left of the pivot. The bar’s moment of inertia about the pivot is

0.24\,\text{kg}\cdot\text{m}^2

. What is the magnitude and direction of the bar’s angular acceleration immediately after the forces are applied? (a)

23\,\text{rad/s}^2

counterclockwise (b)

35\,\text{rad/s}^2

counterclockwise (c)

15\,\text{rad/s}^2

clockwise (d)

8.4\,\text{rad/s}^2

counterclockwise