Vertical Loops Uniform Circular Motion and Gravitation 1. A ball is being spun at the end of a string in a vertical circle. If the mass of the ball is 0.5 kg, the radius of the circle is 0.75 m, and the speed of the ball at the bottom of the circle is 7 m/s, calculate the a. speed of the ball at the top of the loop, b. the force of tension in the string when the ball is at the bottom of the loop, and c. the force of tension in the string when the ball is at the top of the loop