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Re: That jerk again!



Leigh wrote:
. . .
Bob wrote:

Your brakes cannot directly stop the body, they only stop the wheel-axle
system. The body is stopped by 1)the suspension system which links it to
the wheel-axle system, and 2)air friction - nothing else that I can see
in the picture can exert a force DIRECTLY on the body (unless you drag
your feet on the ground and hold on tight!).

Leigh:

I didn't make myself clear. I assume the body comes to rest at the
same instant the wheels do while the car is coasting uphill in neutral
with brakes off. The only change when the brakes are applied is that
the frame of reference in which the car finds itself has a gravitational
field pointing in a slightly different direction.

Leigh

If you did nothing, the car would come to rest and then begin to accelerate
downhill. If you stop the wheel axle system at the moment when v=0, the
body will still begin accelerating downhill and will do so until the
(now fixed to the roadway) suspension link stops it.

-Bob
--
Bob Sciamanda sciamanda@edinboro.edu
Dept of Physics sciamanda@worldnet.att.net
Edinboro Univ of PA http://www.edinboro.edu/~sciamanda/home.html