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

Step-by-step 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`