The magnet is at a gravitational force while the paper clip is at an applied force
<span>Work is required to pull a nucleon out of an atomic nucleus. It has more mass outside the nucleus.</span>
That's the definition of the PERIOD of the vibration.
It's exactly the reciprocal of the vibration's frequency.
Friction is the force you get when you (for example) Rub something with another, it's a force that may generate heat and even some resistance. Another example is rubbing your hands together, they get hot, therefore friction is working, without friction you wouldn't be able to stop moving.
