# How does energy differ from force?

Oct 10, 2015

A force is a push or pull. It is a vector. Energy is something transferred between things that cannot be created or destroyed. It is a scalar.

#### Explanation:

This questions is tricky, mostly because it is so hard to define energy . It is one of those things, where "you know it when you see it ".

You can change the energy of an object if you apply a force over a distance . This is known as work:

$W = F \cdot d$

Force has the units of Newtons. Energy has the units of Joules (or $N \cdot m$).

I like to think of force and energy as two different ways to think about mechanics. Some problems are easier to solve through the lens of work, some problems are easer to solve through the lens of energy.

For example, you drop a rock and it falls to the ground:

Force: The force gravity pulls on the rock, causing an acceleration and increasing the velocity of the rock as it falls.

Energy: The gravitational potential energy of the rock is converted into kinetic energy as the rock falls.

Pick whatever is easier to solve the problem or is appropriate for the chapter in the book your class is working on. Just don't try to apply Force lens and Energy lens for the same problem. You will probably confuse yourself.