To start a la n d er, rou must pul on a o e ou d O nd the peri ee of a nr heel A

Question

To start a la n d er, rou must pul on a o e ou d O nd the peri ee of a nr heel A er you pull t e rope or 0 94 s tlie nywheel is otating at 4 e olutions per second at slows, coming to r:0.24 s atter the disengagement. Assume Donstant acceleration during both spin up anc spin down. ich pont the ope disengages is atten t at start ng the n e does oto k how ever, and the ny heel rope disengages. This at , however, a) Datermina the averagc anguar accecradon durin te D.94- spin-up and agoin during thc 0.24-s spin-down. spin-up 26,73 rad/s rad/s2 spin-down U b What is the maximum angular spsed raached by thc flywhed 25.13 rad' (c) Cetemine the ratio othe number cr revelutions made during spin-up to the number made during spin-down

Explanation / Answer

3) = 4 rev/s * 2 rads/rev = 25.13 rad/s

1) = / t = 25.13rad/s / 0.94s = 26.73 rad/s²

2) = -25.13rad/s / 0.24s = -104.7 rad/s²

4) Use the average velocity and the time:
spin-up: up = ½ * 25.13rad/s * 0.94s = 11.81 rads
spin-down: down = ½ * 25.13rad/s * 0.24s = 3.0156 rads
ratio up / down = 11.81/3.0156 = 3.916
which, not coincidentally, is equal to the ratio of the spin-up time to the spin-down time.

Hope this helps!

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