Inverse and Direct Variation Word Problems - Examples

The reason roller coasters have that name is because the cars "coast" after the first big hill. This means that the whole ride depends on the cars energy it gets after the first hill and doesn't get any boosts.

The energy the car has while it's moving is called "kinetic energy". The equation for kinetic energy is: $$\text{KE} = \frac{1}{2}mv^{2}$$

$m$ is the car's mass and $v$ is the car's velocity. Which quantities have a direct variation between them?