Question

A figure skater begins spinning counterclockwise at an angular speed of 4.5 π rad/s. During a 4.8 s interval, she slowly pulls her arms

inward and finally spins at 7.2 π rad/s.
What is her average angular acceleration
during this time interval?
Answer in units of rad/s
2
.

Answer 1

`\alpha =1.76\ rad/s^2`

Explanation:

Given that,

Initial angular speed of the skater,
`\omega_i=4.5\pi\ rad/s`

Final angular speed of the skater,
`\omega_f=7.2\pi\ rad/s`

Time interval, t = 4.8 s

We need to find her average angular acceleration during this time interval. Let
`\alpha` be the average acceleration of the skater. So,

`\alpha =(\omega_f-\omega_i)/(t)\\\\\alpha =(7.2\pi -4.5\pi)/(4.8)\\\\\alpha =1.76\ rad/s^2`

So, her angular acceleration is
`1.76\ rad/s^2`.