posted by Luis .
A simple pendulum consists of a light string 1.70 m long with a small 0.490 kg mass attached. The pendulum starts out at 45^\circ below the horizontal and is given an initial downward speed of 1.50 m/s.
At the bottom of the arc, determine the centripetal acceleration of the bob.
At the bottom of the arc, determine the tension in the string.
See my later response to the same question.
Your subject is spelled physics. That would be a good place to start learning the subject.