physics
posted by Colin .
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 2.6 times her weight as she goes through the dip. If r = 20.0 m, how fast is the roller coaster traveling at the bottom of the dip?

M (g + V^2/R) = 2.6 M g
V^2/R = 1.6 g
They have given you the value of R, and you know what g is.
Solve for V.