PHY120 study review

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 15π rad/s in 6.6 s. At this point, the lid is opened, and a safety switch turns off the washer. The tub slows to rest in 16.6 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

Thank you for the opportunity to help you with your question! the solution is as such:

Thank you for the opportunity to help you with your question! the solution is as such:

when the lid is opened, u= 16 π rad/s

final velocity v= 0 π rad/s 

we know, v= u + at  (here a denotes alpha i.e. acceleration for circular motion)

where t= 16.6s

  so a = 0.95 π rad/s ^ 2

now v^2 = u^ 2 + 2aS

so, S= 145.03 rads.

1 revolution require 2 π rads

so, this is equivalent to 145.03/2 so it will take almost 72.5 revolutions in stopping.


Please let me know if you need any clarification. I'm always happy to answer your questions.awaiting a positive feedback. thank you.
Jun 23rd, 2015

I tried to put the value 72.5 in my homework web page and it was the wrong answer. Is there another way to solve this problem?


Jun 23rd, 2015

try 72 0 or 73

Jun 23rd, 2015

we know, v= u + at  (here a denotes alpha i.e. acceleration for circular motion)

where t= 16.6s

  so a = 0.90π rad/s ^ 2

now v^2 = u^ 2 + 2aS

so, S= 153.0 rads.

1 revolution require 2 π rads

so, this is equivalent to 153.0 /2 so it will take almost 76.5 revolutions in stopping.


Please let me know if you need any clarification. I'm always happy to answer your questions.awaiting a positive feedback. thank you.

Jun 23rd, 2015

u can try with 76 or 77. for any doubts.i am happy  to guide you further

Jun 23rd, 2015

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Jun 23rd, 2015
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Jun 23rd, 2015
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