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 Author Topic: Circular motion Qu: a motorcyclist travel in vertical wall  (Read 28058 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
bocan007
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 « Embed this message on: December 29, 2005, 11:30:45 am »

A motocyclist moving fast enough may travel in a horizontal circle on the inside surface of a vertical cylinderical wall(a "wall of death").
In this case,the motocyclist must make a small angle to the wall to balance the moment by the friction and prevent toppling

My question is why in this case,the normal reaction doesn't perpendicular to the contact suface?Could you show me the force diagrame in this case?

(how can i post a image?)
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Fu-Kwun Hwang
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 « Embed this message Reply #1 on: December 29, 2005, 02:10:02 pm » posted from:Taipei,T'ai-pei,Taiwan

For a motorcycle to turn on the rode,
there is a normal force perpendular to the ground and also a friction force parallel to the ground.
So the net force is not perpendular to the ground.
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bocan007
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 « Embed this message Reply #2 on: December 29, 2005, 03:15:27 pm »

I mean a motorcycle travel inside a vertical cyclindrical wall like the wall of death.
The motorcyclist need to lean an angle to the wall to pervent tippling
My question is in this case,why the normal reaction acted by the wall on the motorcycle doesn't perpendular to the wall(the contact surface)
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Fu-Kwun Hwang
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 « Embed this message Reply #3 on: December 29, 2005, 05:27:35 pm » posted from:Taipei,T'ai-pei,Taiwan

The mormal force is still perperdular to the surface (equal to the mV^2/R)
and the friction force is equal to the weight (mg).
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bocan007
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 « Embed this message Reply #4 on: December 29, 2005, 05:36:51 pm »

Does the normal reaction still point to the centre even if the motorcyclist lean to the vertical wall?
Will the direction of the normal reaction change when the motorcyclist lean to the vertical wall?
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Fu-Kwun Hwang
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 « Embed this message Reply #5 on: December 29, 2005, 05:43:31 pm »

The normal force is always point to the center, that is the reason we call it normal force.
But the net force (normal force + friction force) is not normal to the wall.
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 « Embed this message Reply #6 on: January 02, 2006, 10:45:57 am »

So there is a centripetal force acting on the motor driver
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Fu-Kwun Hwang
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 « Embed this message Reply #7 on: January 02, 2006, 12:18:31 pm »

There is no circular motion without the wall.
The normal force provided by the wall let the motorcycle moves in a circlar path.
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Knowledge and practice are one. ..."Wang Yang Ming (1472-1529, Chinese Philosopher) "