Why was the second law of motion invented?

Second law of motion is the quantitative definition of the force and one of the most important laws in physics. Most of the classical physics revolve around the concept of force and so quantitative measurement of it was inevitable, irreplaceable.

Invention of Second law of motion was a need.

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.

the answer is ampere

the ampere is used to measure electricity. an ampere is a unit of electric current equal. a unit of measure for the flow of current in a circuit. one ampere is the amount of current flow provided when one volt of electrical pressure is applied against one ohm of resistance.