Homework Help Forum: college physics

Posted by Ashley on Wednesday, November 4, 2009 at 1:32pm.

A small mass m slides without friction along the looped apparatus shown in Fig. 6-39. If the object is to remain on the track, even at the top of the circle (whose radius is r), from what minimum height h must it be released? (Answer in terms of r.)

• college physics - bobpursley, Wednesday, November 4, 2009 at 1:56pm

  I can only imagine what the figure is, and my crystal ball is not working. I assume h is measured from the bottom of the loop, so the PE going into the mass is h-2r measured at the top. So that is equal to KE at the top. mg(h-2r)=1/2 m v^2 so solve that for v^2 Now, at the top, the force on the track is mg-mv^2/r, and that to stay on the track must be non negative.0<mg-mv^2/r so put in v^2 from before, and solve for h.

  
  

• college physics - Ashley, Wednesday, November 4, 2009 at 3:25pm

  Thanks that helps alot

  
  

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