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JDK1.0.2 simulations (1996-2001) => Dynamics => Topic started by: bocan007 on December 29, 2005, 11:30:45 am



Title: Circular motion Qu: a motorcyclist travel in vertical wall
Post by: bocan007 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?)


Title: topic324
Post by: Fu-Kwun Hwang on December 29, 2005, 02:10:02 pm
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.


Title: topic324
Post by: bocan007 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)
please answer me ,thanks


Title: topic324
Post by: Fu-Kwun Hwang on December 29, 2005, 05:27:35 pm
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).


Title: topic324
Post by: bocan007 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?


Title: topic324
Post by: Fu-Kwun Hwang 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.


Title: topic324
Post by: cookie on January 02, 2006, 10:45:57 am
So there is a centripetal force acting on the motor driver ???


Title: topic324
Post by: Fu-Kwun Hwang 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.