ENERGY!
Nah, I get Energy. Go to Work and Power instead.
Worksheets and solutions to problems

Car and Ramp Lab Simulation -> http://scratch.mit.edu/projects/stickmanstan/1586517

THERE ARE MANY TYPES OF ENERGY!
Chemical energy is stored in the bonds between molecules.
Nuclear Energy is stored in the bonds between particles in the nucleus.
Electrical energy is based on the location of charged particles in electrical fields.
Heat itself is nothing but the energy contained in moving molecules. BUT,

The two types of energy that we (and most of your 7th or 8th grade teachers) focus on are
GRAVITATIONAL POTENTIAL ENERGY (GPE) or more simply (PE) though this is misleading.
and KINETIC ENERGY. (KE)

COMBINING KE and PE we are given what is known as TOTAL MECHANICAL ENERGY. And the neat thing about
TME (not time) is that there is a law called the law of Conservation of Energy that says energy cannot be created or destroyed, so the total amount of energy in a closed system remains constant.

This means that Total Mechanical Energy is always the same!

Take a look. When a diver climbs a ladder to the top of a high dive, the Wheaties that he had for breakfast gave him chemical potential energy, which he then used to raise himself up against the gravitational pull of the Earth. He has given himself the ability to fall down to the ground. He has the ability (potential) to do work. So we say he has Potential Energy.

When he falls from this height, he will come back toward the ground. Which lowers his potential energy. But he will be going faster, so now he will have an increased kinetic energy, an energy based on how fast you are going. The farther down he falls, the faster he will be going, so the more kinetic energy he will have.


We see at the halfway point, he is at half the original height, so he'll have half the Potential Energy. Because the TOTAL MECHANICAL ENERGY needs to remain constant, we see that he will also have half the final kinetic energy.

Of course, not all energy is converted from Gravitational Potential Energy to Kinetic Energy back to Potential Energy.
Check out this car.


Here, the kinetic energy comes from the chemical potential energy in the gasoline. When we heat up the gasoline vapor, it rips apart chemical bonds and gives off a lot of stored energy. We use that energy to turn your axle and the car moves increasing its kinetic energy. When the car stops, the kinetic energy that it had is going to change form once again, but this time it will not return to potential energy, it will instead become heat as the brakes are applied to the wheels to stop the car. That heat leaves the brakes and warms the air around them and the energy is no longer in our system.

Learn more about this project