A small cart of mass m enters the bottom of a vertical circular loop of radius 5.0m with speed v0. What is the minimum value of v0 so that the cart just maintains contact with the track at the top of the loop? (Take g=9.8ms−2.)
a) 17.1ms−1
b) 12.1ms−1
c) 15.7ms−1
d) 14.0ms−1