Wednesday
February 10, 2016

# Homework Help: physics - rotational motion

Posted by Lauren on Friday, April 22, 2011 at 2:50pm.

A small car of mass, m, is release at height, h, on a steel track. the car rolls down the track and through the loop of radius, R. at the end of the rack, the car rolls off the track, which is positioned at height, H, above the floor. neglect friction and the small amount of rotational motion of the wheel of the car. Solve in terms of h, m, R, H, and g.

a. find the velocity of the car at the bottom of the loop.

b. find the velocity of the car at the top of the loop.

c. determine the height, h, at the top of the hill such that the car just barely makes contact with the loop at the toop of the loop as it goes through the loop.

d. when the car is moving at minimum speed, what provides the centripital forve on the car:
i. the bottom of the loop
11. the top of the loop
iii. the side of the loop.

e. determine the distance from the end of the track that the car will land on the floor.

i don't know how i would go about this problem, especially since there are no quantitative information given none other than variables.
• physics - rotational motion - bobpursley, Friday, April 22, 2011 at 3:12pm

a) KE at bottom= PE at top
1/2 m v^2=mgh solve for v.
where h is the distance from the starting point to the end point.
b) 1/2 m v^2=mg(h-2R)
c) at the top of the loop.

v^2/r=g as a minimum, so figure v^2.Then, using that v^2, 1/2 mv^2=mg(heighttostart) I dont understand the question.
e) figure v, that is the horizontal speed.
then figure the time to fall H
H= 1/2 g t^2 find t.

horizontal distance= v*t
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