Question

An engine flywheel initially rotates counterclockwise at 5.91 rotations/s. Then, during 22.3 s, its rotation rate changes to 3.17 rotations/s clockwise. Find the flywheel's average angular acceleration (including its sign) in radians per second squared. Define counterclockwise rotation as positive.

Answer 1

Answer:$2.55 rad/s^2$ ccw

Explanation:

Given

$N_1=5.91 rpm$ (ccw)

$\omega _1=2\pi 3.17\cdot 5.91=37.13 rad/s$ (cw)

t=22.3 s

$N_2=3.17 rpm$ (cw)

$\omega _2=2\pi 3.17\cdot 3.17=19.92 rad/s$ (cw)

$\omega _2=\omega _1+\alpha \cdot t$

where $\alpha$is the angular acceleration

$-19.92=37.13+\alpha \cdot 22.3$

$\alpha =-2.55 rad/s^2$