Pendulum question about conservation of energy?

Question

Why is that if energy is conserved the string of a pendulum never reaches the height it was dropped from?

Answer 1

It will come very close. A pendulum is usually a very low loss system which makes it an excellent candidate for looking at conservation of energy but there are some losses.

1. there will be some small amount of air friction
2. the support for the string may flex a bit and may have some loss.
3. The string may stretch a bit more at the bottom of the swing than at the top (this can have some loss).

Even in a good system one can never quite break even. Entropy strikes again.

Answer 2

I believe it is used to do the work of swinging. inertia is opposed by other forces such as friction gravity and the like
how the energy is absorbed or converted will require someone with more expertise than I some is lost in heat but as the potential energy is effected by gravity the gravity prevails till there is no more room to act thus your kinetic energy is left as potential energy . the ball hanging is still under the force of gravity as it appears to remain still so I imagine the potential energy that became kinetic is returned to potential energy as the hanging ball is at rest stopped by the string opposing the potential force of gravity