A 10-KG cart moving at 5 m/s collides with a 5 KG cart at rest and causes it to move 10 m/s. Which principal explains the result?

energy transfer. or, kinetic energy.

Explanation:

when something collides with another, it transfers kinetic energy to the other it collided with, making it move.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach