A spring is used to measure the centripetal force. Since a spring will exert a restoring force equal to the force applied to it, the centripetal force can be verified by measuring the amount of force need to stretch the spring a distance. We will assume a spring constant of 9m/N, That is it 1 N of force to move the spring 9 meters. For 6 different radius, covering the radius scale, calculate the force needed to stretch the spring.