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AP Physics review help?
a figure skater is spinning with her arms extended at 180 revolutions per minute. she pulls her arms in over a course of 1 second and speeds up to 540 revolutions per minute. what is he initial and final angular velocity?
2 Answers
- electron1Lv 74 years ago
As she revolves one time, she rotates an angle of 2 π radians. One minute is 60 seconds.
1 rpm = 2 π/60 = π/30 rad/s
To convert rpm to rad/s, multiply by this fraction.
ωi = 180 * π/30 = 6 * π
This is approximately 18.8 rad/s.
ωf = 540 * π/30 = 18 * π
This is approximately 56.5 rad/s. Since the increase of angular velocity occurred in one second, you can use the following equation to determine her angular acceleration.
ωf = ωi + α * t
α = 18 * π – 6 * π = 12 * π
Her angular acceleration is approximately 37.7 rad/s^2. I hope this is helpful for you.
- Anonymous4 years ago
Initial angular velocity = 180 rev/min
1 rev/min = (2 π / 60) rad/s
Initial angular velocity = 180rev/min × (2 π rad/s / 60) / (rev/min)
= 6 × 3.14 rad/s
= 18.84 rad/s
Do same like this for final angular velocity (= 540rev/min)
