3.4 Kinetic Energy

Kinetic energy is the energy of motion. To derive the equation for kinetic energy, KE, let us imagine an object of mass m tht is dropped to earth from a height h. We begin with two previously discussed equations:

Combining the two, we get

Next, we reintroduce an equation from Unit 1:

Since, in the case of our object, v₁ is 0, we can simplify to get

Substituting this into the previous equation, we find that

We derive the equation for kinetic energy by substituting KE for work:

(Note: Non-translational kinetic energy, or rotational kinetic energy, will be discussed in Unit 4.)