Question about centripetal force and rollar coasters?

Question

Why is the apparent weight of a person on the top and bottom of the loop of a rollar coaster different?
I know it has something to do with centripetal force (and gravity)...thanks!

Answer 1

Of course, centripetal/fugal force isn't a real force, it's just a perceived force caused by acceleration.

On flat ground, your weight is given by the equation F=ma. Mass times acceleration. Acceleration is given by the acceleration due to earth's gravity (g = -9.8m/s^2). When you are going around a loop, this pull still exists.

However, you are also undergoing other acceleration, (remember that acceleration simply means a rate of change in direction) caused by the roller coaster changing direction (by going through the loop).

Your weight with respect to the roller coaster car (like, the weight of you getting pushed into the seat) is then given by the sum of the forces of gravity and the "centripetal" force:

F = m(a1) + m(a2), where a1=g (which is -9.8)
So we can rewrite it as:
F = m(a2 - 9.8) where a2 is the acceleration caused by the roller coaster going in the loop.

At the top of the loop, gravity is pulling you down, but the centripetal force is pulling you up, into your seat. This is what can cause you to feel "weightless"-- if the two acceleration values are identical for a split-second, you will literally be weightless for that very small amount of time.

Who knew the amusement park could be so geeky, huh?

Answer 2

That person has centrifugal force pushing him up at the top of the turn. This makes gravity have less of an effect on him

Answer 3

centrefugal....inertia...an object in motion ..newtons laws