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Homework Help: Horizontal Circular Motion

  1. Mar 9, 2007 #1
    1. The problem statement, all variables and given/known data
    A microwave's turntable spins 3.0 revolutions per minute. It has a 250.0g cup of coffee placed 15.0cm from its centre. Find its period of revolution, its tangential velocity and the centripetal force on the cup.

    2. The attempt at a solution
    period of revolution [tex]\frac{{60}}{3} = 20[/tex] seconds
    tangential velocity [tex]\frac{{2\pi r}}{T} = \frac{{2\left( \pi \right)\left( {15} \right)}}{{20}} = 4.7123\,m\,s^{ - 1} [/tex]
    centripetal force [tex]\frac{{mv^2 }}{r} = \frac{{0.25\left( {\frac{{2\left( {15} \right)\left( \pi \right)}}{{20}}} \right)}}{{15}} = 0.0785\,N[/tex] towards the centre of the circle


    I was wondering if somebody could kindly take the time to look over my working and see if it is correct. Thank you greatly for your time and effort.
    unique_pavadrin
     
  2. jcsd
  3. Mar 9, 2007 #2
    I didnt check the numbers but the rest looks okay. What is providing the centripetal force here?
     
  4. Mar 9, 2007 #3
    the centripetal force is provided by the spinning turntable of the microwave if I'm not mistaken.
     
  5. Mar 10, 2007 #4
    i presumed it is friction that is providing the centripetal force.....
     
  6. Mar 10, 2007 #5
    friction of.....
     
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