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A disc starts from rest and, on application of a torque, acquires an angular acceleration alpha = 3t - t² (SI units). Find its angular velocity after t = 2 s.

1. 2 rad/s
2. 4/3 rad/s
3. 6 rad/s
4. 10/3 rad/s

Correct answer: 10/3 rad/s

Solution

Integrating alpha = 3t - t² gives omega = (3/2)t² - (1/3)t³; at t = 2, omega = 6 - 8/3 = 10/3 rad/s.

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