The angular speed of a flywheel is uniformly increased from 60 rpm to 1200 rpm in 10 s. How many revolutions are completed during this time? (Values are reproduced from the printed question.)
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The angular speed of a flywheel is uniformly increased from 60 rpm to 1200 rpm in 10 s. How many revolutions are completed during this time? (Values are reproduced from the printed question.)

G1 Physics · Accepted Answer

Step 1: For uniform angular acceleration, the average rotational frequency is (f(initial) + f(final))/2. Step 2: As PRINTED in the question, f(initial) = 60 rpm = 1 rev/s, f(final) = 1200 rpm = 20 rev/s. Step 3: The average frequency = (1 + 20)/2 = 10.5 rev/s. Step 4: Number of revolutions N = f(average) × t = 10.5 × 10 = 105 revolutions. This is not any offered option. Step 5: The supplied PDF solution instead takes the initial speed as 600 rpm (10 rev/s). That would give N = [(10 + 20)/2] × 1…