A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to

A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to

Right Answer is:

50

SOLUTION

Initial angular velocity, ω₀ = 0 [because flywheel moves from rest ]

Final angular velocity, ω = 1000 rpm = 1000/60 rev/sec

Time taken, t = 6 sec

From Rotational Motion

ω = ω₀ + αt

Where α is angular acceleration.

1000/60 = 0 + α6
α = 1000/360 = 100/36 = 25/9 rev/s²

Now

θ = ωt + 1/2αt²
= 0 + 1/2 × 25/9 × (6)²
= 1/2 × 25/9 × 36
= 1/2 × 25 × 4
= 50 rev

Hence, number of revolutions = 50

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