A small car with a mass of $0.8\; kg$ travels at constant speed on the inside of a track that is a vertical circle with a radius of $5.0\ m$. If the normal force exerted by the track on the car when it is at the top of the track is $6.0\; N$, What is the speed of the car?

Question

$\begin{array}{1 1} 21.7\;m/s \\ 9.3\;m/s \\ 2.7\;m/s \\3.6\;m/s \end{array} $