1. The problem statement, all variables and given/known data A pendulum with a bob on the end is attached to a stand. The stand has a rod sticking out such that when the string of the pendulum strikes it, it starts to undergo circular motion. Consider the bob being released from a height such that when it strikes the rod, it only just manages to complete one rotation (i.e. any smaller height and it would fail to complete a full rotation). If the tension in the string it zero when it is at its highest point discuss, without calculation, the tension in the string at its lowest point in terms of the weight of the bob. 2. Relevant equations ac = v^2/r 3. The attempt at a solution I would say that the tension in the string for question two must be higher than twice the weight. This is because the centripetal force at the top is mg if the bob is weightless. Assuming it remained at mg would mean that the centripetal force would be twice mg at the bottom. However, using conservation of energy, the bob must have more kinetic energy at the bottom and therefore more velocity and therefore a greater centripetal force than 2mg. So in conclusion this is not circular motion hence Fc at the bottom is more than 2mg, is that right?