Energy conservation and the simple pendulum

A simple pendulum is composed of a mass m connected to a string of length / that deviation from the vertical. Assume the acceleration due to gravity is g. - - - - m a. Choose a system with which to model the pendulum that is isolated (e.g. its total energy is conserved). Explain your choice of system and how you can tell its energy is conserved. b. Find an expression for the velocity of the pendulum bob (the red sphere) as it moves through the base of its swing (e,g, at the instant the pendulum string is vertical). The expression should be in terms of the given quantities m, l, 0 and g. Explain your conclusion. c. For part b, express the tension in the string in terms of he given quantities m, l, 0 and g, at the instant the pendulum moves through the base of its swing. Explain your work and include a force diagram. (Hint: consider the motion as being along the arc of a circle)