Answer:
v = 14.92 m/s
Explanation:
First, make a free body diagram and see the forces in the y-direction.
Use Newton's 2nd Law F = ma to replace ∑F_y with m * a_y.
The acceleration in the y-direction is the centripetal acceleration, a_c = v^2/r.
The normal force is 0 because this is where the rollercoaster is not falling off the track yet not touching the track.
The masses cancel out.
Solve for v to find the speed of the rollercoaster at the top of the loop.
The minimum speed the coaster must have at the top of the loop to not fall off the track is 14.92 m/s.