Problem 2- A 350 kg roller coaster starts from rest at point A and slides down the frictionless loop-the-loop shown in the figure.

a) How fast is the roller coaster moving at point B?
b) How hard does it press against the track at point B?

2 answers

Use energy principles on A.
b. force=mg+mv^2/r
A=mgh
= 350 x 9.8 x 25
= 85750 J
B=MGH
= 350 x 9.8 x 12
= 41160 J

1/2mv^2= A-B
v=√(2(A-B)/m)
=16 m/s

F= (mv^2)/r - mg
= 14933.3333 - 3430
= 11503.333 N or simply 1.15 x 10^4 N