what is kinetic energy

Question

i want to know more about kinetic and potential energy

 

Answer 1

I don't know what precisely you are asking about them, so let's start with the basics:

Kinetic energy: the energy of motion. This is why the formula for kinetic energy is:

K_e = mV² / 2      -- You need mass and motion to have kinetic energy.

Potential energy:  energy stored in an object, usually by its relationship to a gravitational field. This is why the formula is:

P_e = m*g*h       -- Note that you still require mass, but instead of motion, you require a gravitational field and at least some distance from its source. 

Neither one prevents the other. If you toss a ball in the air, it slowly transforms much of its kinetic energy into potential energy until it stops rising. When it falls, it begins with purely potential energy that slowly returns to kinetic form. At any given time, it will probably have a mix of the two. Some energy should be lost to friction with the air, surrendering a little of that oomph to other forms like heat.

Answer 2

This id the very basics, but hopefully the layman will help you visualize.

Potential energy is the type of energy that is stored up and ready to perform work on an object. One common form is gravitational, where an object--like say a bowling ball--is lifted up and held there. Another form of potential is elastic, where something is bent from its original position into a new one, such as a bow pulled back holding an arrow.

Kinetic energy is the release of the potential to do 'work,' or movement energy. In the gravitational potential energy example, the bowling ball is released, and it falls back down to the ground. In the elastic potential energy case, you let go of the bow string, and the bow rights itself. That energy is transferred to the arrow and lets it fly.

 

Kinetic energy and potential energy is essentially a zero-sum situation, though you must not forget about friction, which converts some of that energy into heat. That's why when you put a ball at the top of a U-shaped ramp that each time it makes a pass to the other side, it doesn't reach quite as high as the starting drop from before: the ball pressing against the ramp as well as the curve of the ramp forcing the ball to change directions induces friction, causing some of that kinetic energy to become lost as heat energy as it rises up the other ramp end (turning that kinetic energy back into potential energy, until it drops back down again to become kinetic energy once more).

 

This continues until all of the energy is turned into heat and the ball stops at the center (re: bottom) of the ramp.