A hard disk in your computer spins at 5400 rpm. If this disk turns through 12 revolutions before coming to a stop, find
a. the disk’s angular acceleration (rad/s2) and b. the time it takes to stop.
- NCSLv 71 month ago
ω = 5400rev/min * 2π rads/rev * 1min/60s = 565 rad/s
a. ω₀² = ω² + 2αΘ
0² = (565rad/s)² + 2 * α * (12*2π rads)
α = -2120 rad/s²
and you might not need the sign in your answer.
b. easiest is
t = Θ / ω_avg = 12*2π rads / ½*565rad/s = 0.27 s
but you could also use
Θ = ω₀ + α*t
since you know Θ, ω₀ and α
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