Circular motion

Can u pls tell me from which paper this is?

One end of a string is secured to the ceiling and a metal ball of mass 50g is tied to its other end. The ball is initially at rest in the vertical position. The ball is raised through a vertical height of 70cm. The ball is then released. It describes a circular arc as it passes through the vertical position(pendulum)
The length of the string is 1.5m.
a) ignoring the effects of air resistance, determine the speed v of the ball as it passes through the vertical position
b) Calculate the tension T in the string when the string is vertical
c) Explain why your answer to b is not equal to the weight of the ball