posted by jessie .
When the roller coaster is at the top of the loop, why doesn’t the person fall off the roller coaster?
What forces are acting on the person when the roller coaster is going round the loop? Is it gravitational force and normal force?
well yes sort of but the normal force you are talking about is that giving centripetal acceleration
at the top of the loop, m g the weight is down
However a normal force in the down direction of m v^2/R is required to keep the person moving in the circular loop.
So as long as m v^2/R is greater than m g, the person does not fall out.
so in the end
v^2/R >/= g
is the condition for not falling out of the roller coaster.