# Roller Coaster question

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1. Dec 23, 2016

### Schaus

1. The problem statement, all variables and given/known data
Jessie (m=56.2 kg) is traveling at a speed of 12.8 m/s at the top of a 19.5-m high roller coaster loop.

a) Assuming negligible losses of energy due to friction and air resistance, determine Jessie's total mechanical energy at the bottom of the loop (h=0 m). (ans: 1.53 x 104 J)
b) Determine Jessie's speed at the bottom of the loop. (ans: 23.4 m/s)
c)What force does Jessie feel from her seat at the bottom of the loop? (ans: 3707N)
2. Relevant equations
F=ma
ac=v2/r
mgh
1/2mv2
3. The attempt at a solution
I figured out a) with mgh+1/2mv2=Efinal.
I figured out b) with using energy from a) 1.53 x 104= 1/2mv2
But I can't figure out c).
I tried using ac=23.42/19.5m to find my acceleration then multiply the mass but the number isn't close to the weight I need.

2. Dec 23, 2016

### TomHart

It looks like you used the diameter, as opposed to the radius.

3. Dec 23, 2016

### TSny

2nd law: Fnet = ma. Note the "net" here.

4. Dec 23, 2016