Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.

##
Kinetic Energy and Work

- The
**kinetic energy** of an object is defined as
2
KE = 1/2 * m * v

- The kinetic energy of an object depends on its velocity.
To change its velocity, one must exert a force on it.
It turns out there's a connection between the force
one applies to an object and the resulting change in its
kinetic energy:
KE(final) - KE(initial) = (force) (distance)

where the **force** is applied over some **distance**.
- We can this combination of force and distance
**work**, so
KE(final) - KE(initial) = Work done on object

- In fact, it's a little more complicated than that.
Only that component of the force which runs in the same
direction as the displacement causes a change in the
kinetic energy, so really
KE(final) - KE(initial) = (force parallel to displacement) (distance)

- Another way to write this is with vectors
**F** for force and
**d** for displacement. Then
KE(final) - KE(initial) = F (dot product) d
= F * d * cos(alpha)

where **alpha** is the angle between vector **F** and
vector **d**.

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Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.