Energy

There are different forms of energy, like electrical, thermal and chemical, but I'd like to start off with mechanical energy.

Well, what is energy? Energy is the amount of work that gets done. It is the amount of force applied to something for a given distance. There was this saying in my high school physics class: "Work is mad". That means that the amount of work you do (energy you use) on an object is equal to the mass, acceleration and distance multiplied together. I'll give you two formulas right now.

E=mad
E=Fd

The unit for energy is called the joule. It's abbreviated as J and can be written in terms of the unit's we've already learned about.

1J=1Nm
1J=1 m²kg/s²

OK, here's a problem: We have a crate that weighs 500 Newton that needs to be lifted 39 meters to a 13th-story window. How much energy will it take to lift straight up?

F=500kg
d=39m

E=Fd
E=500N·39m
E=19500 N·m
E=19,500 J

So you'd need to use 19,500 joules of energy to get the crate up to the window.