"A 0.400-kg pendulum bob passes through the lowest part of its path at a speed of 3.00 m/s. What is the tension in the pendulum cable at this point of the pendulum is .8 meters long?" I would like to ask for some help on understanding centripetal force in this particular situation. I realize gravity is pulling down on the bob, while tension is counteracting gravity, and centripetal force is also counteracting gravity. I would like someone to explain to me why the sum of the forces here is the total centripetal force, or Tension minus force of gravity.