posted by Garcia .
A roller coaster track is designed so that the car travels upside down on a certain portion of the track as shown in the figure below. What is the minimum speed the roller coaster can have without falling from the track? Assume the track has a radius of curvature of 20 m.
The force of the centripetal acceleration must be greater than or equal to the force of gravity, or
m * v^2 / r >= mg
v^2 / 20 >= 9.8
solve for v