A disc is rotating at a rate 1200 rpm. it is stopped bu applying a constant torque in 5 second.number pf revolution made by the disc during stopping process?
Answers
Explanation:
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Answer:
The number of revolutions made by the disc during the stopping process = 50.
Solution:
Initial velocity, v = 1200 rpm = 1200/60 rps
= 20 rps (rotations per second)
Initial angular velocity, ω₁ = 2πv
= 2π(20)
= 40π rad/s
The disc is stopped by applying a torque for 5 seconds.
∴ Final angular velocity, ω₂ = 0 rad/s
Time, t = 5 seconds
Using the first equation of rotational motion, we have
ω₂ = ω₁ + αt
where α = Angular acceleration
(0) = 40π + α(5)
0 = 40π + 5α
5α = -40π
α = -40π/5
α = -8π rad/s²
Now using third equation of rotational motion, we have
ω₂² - ω₁² = 2αθ
where θ = angular displacement
(0)² - (40π)² = 2(-8π)θ
-1600π² = -16πθ
θ = (-1600π²)/(-16π)
θ = 100π rad
Number of revolutions made by the disc during stopping process, N = θ/2π
N = 100π/2π
N = 50 revolutions
Hence, 50 revolutions are made by the disc during the stopping process.
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