Originally Posted by

**rcmango** I believe this is another Verticle circular motion problem, they still confuse me, why is it i must add the net forces for the answer, and do i use an equation (m * v^2) / r more than once?

please help, i'm not sure what is the logic behind the equation.

heres the problem:

A roller coaster at an amusement park has a dip that bottoms out in a vertical circle of radius r.

A passenger feels the seat of the car pushing upward on her with a force equal to twice her weight as she goes through the dip.

If r = 16.5 m, how fast is the roller coaster traveling at the bottom of the dip?

in m/s