- #1

ScullyX51

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- 0

## Homework Statement

A roller-coaster has a mass of 500 kg when fully loaded with passengers. The car passes over a hill of radius 15 m. When at the top of the hill, the car has a speed of 8.0 m/s. WHat is the force of the track on the car at the top of the hill?

## Homework Equations

F=ma

## The Attempt at a Solution

I drew an FBD: wtih mg pointing down, N pointing up and static friction pointing to the left. ( I think this may be wrong, but I figured it may need static friction to stay on the track).

Then when broken into i and j components I got:

i= -M

_{s}N=-MV

^{2}/r ...(because the acceleration is centripical)

then for j:

I have N-mg=0

N=mg

and since it was asking for the force of the track on the car, I thought this was the normal force, so I just plugged in the values for m ang, and got 4.9 kN up. This is wrong, it is saying the correct answer is 2.8 kN up. Any suggestions on where I went wrong?