This preview shows page 1. Sign up to view the full content.
7.97. Set Up:
At the top of the loop, the net force needed to produce the centripetal acceleration,
must be equal to or greater than the gravitational force for the car to remain on the track. Thus, a force balance results
in
or
Next calculate the height,
h
, necessary to produce this speed by applying
conservation of energy,
Solve:
The height must be at least
Reflect:
If
the car is moving too slowly at
B
to stay on the track. In that case,
gravity provides more downward force than is needed to maintain the circular path, and the car falls out of the circle.
If
then at
B
more downward force than gravity alone is needed and this additional downward force is sup
plied by the normal force that the track exerts on the car.
7.98. Set Up:
First apply conservation of energy to find the kinetic energy of the wood as it enters the rough
section:
or
Then determine the distance traveled using the workenergy relation,
where
and
For part (b), use the same relation
and the calculated distance to find the frictional work.
Solve: (a)
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '07
 Shoberg
 Acceleration, Force

Click to edit the document details