##### Physics word problem

 Physics Tutor: None Selected Time limit: 1 Day

The tub within a washer goes into its spin cycle, starting from rest and reaching an angular speed of 16π rad/s in 7.2 s. At this point, the lid is opened, and a safety switch turns off the washer. The tub slows to rest in 16.7 s. Through how many revolutions does the tub turn? Assume constant angular acceleration while the machine is starting and stopping. Answer in units of rev

Jun 23rd, 2015

Figure change in angular acceleration to slow down

α = ω/t
α = 16[pi] rad/s /16.7 s
α = 6.98 r/s^2

Plug into the general equation
θ =  ωt - 1/2 t^2
θ = 16*pi*7.2  - 1/2*6.98*7.2^2
180.99 /2 pi = 33 revs

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Jun 23rd, 2015

wait the above calculation is not correct

Jun 23rd, 2015

α = ω/t
α = 16[pi] rad/s /16.7 s
α = 3 r/s^2

Plug into the general equation
θ =  ωt - 1/2 t^2
θ = 16*pi*16.7  - 1/2*3*16.7^2
421.098 /2 pi = 67.02 revs

Jun 23rd, 2015

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Jun 23rd, 2015
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Jun 23rd, 2015
Dec 10th, 2016
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