# Centripetal Force question

1. Jun 12, 2009

### Fisicks

"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.

2. Jun 12, 2009

### Staff: Mentor

It sounds like you are thinking of centripetal force as if it were a third force on the bob. It's not. The only forces acting on the bob are tension and gravity. "Centripetal force" is just a name for the radial component of the net force.

3. Jun 12, 2009

### Fisicks

thank you very much, that's why i was so confused. Centripetal force is just another name for net force, but in angular motion!

4. Jun 12, 2009

### diazona

For the radial component, yes. You could have a tangential component of force too, but it's not centripetal.