Revolutions per minute

  • Thread starter Tina20
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Homework Statement



An electric-generator turbine spins at 3460.0 rpm. Friction is so small that it takes the turbine 14.9 min to coast to a stop. How many revolutions does it make while stopping? (Do not include a unit with your answer.)

Homework Equations



rev/min * 1min/60sec = rev/sec
T (period) = 1/(rev/sec)
w (omega) = 2pi/T
wf = wi + at/r *delta t where at is tangential acceleration and r is radius


The Attempt at a Solution



346.0rev/min * 1min/60sec = 57.66 rev/sec

T = 1/57.66 = 0.0173 seconds

w = 2pi/T = 2pi/0.0173 sec = 363 rad/sec

So I did all the above, but to solve for tangential acceleration I need a radius, which is not given in the question. Once I find tangential acceleration, I can substitute it into the following equation:

Theta final = Theta initial + wi * delta t + ar/2r (delta t ^2)

and theta final can be converted into the number of revolutions.

This is a non-uniform circular motion question.

Please help :)

Tina

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Kurdt
Staff Emeritus
Science Advisor
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