alleryStart learning →A reel starts from rest with an angular acceleration of 110 rad/s^2 held for 2.00 s. How many revolutions does it turn through?
A220 rev
B35.0 rev
C110 rev
D70.0 rev
Answer & Solution
Correct answer: B. 35.0 rev
1. Angle turned comes from theta = omega_0 t + 0.5 alpha t squared.
2. Starting from rest, omega_0 = 0, so only the second term survives.
3. Substituting, theta = (0.500)(110 rad/s^2)(2.00 s) squared = (0.500)(110)(4.00).
4. That gives theta = 220 rad.
5. One revolution is 2 pi rad, so divide by 6.283 to convert.
6. theta = 220 rad / 6.283 rad per rev = 35.0 rev.
7. Answering 220 rev quotes the angle in radians and skips the conversion entirely.
_Source: OpenStax College Physics (CC BY 4.0), Ch 10 "Rotational Motion and Angular Momentum", section 10.2 Kinematics of Rotational Motion_
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