To make physics simpler, an object can be approximated to act like it has all its mass concentrated at a single point. This single point is called the 'center of mass'. If the density of the object …

## Physics of Freeway Entrances

On round freeway turnouts there are almost always signs that say to slow down to a lower speed. The reason for this is that the frictional force of the tires on the road will not always be enough to …

## Momentum, Baseball Bats, & Superstition

In any given system the total momentum will remain constant. For the case of Sammy Sosa, a corked bat is lighter and might therefore be swung faster, but momentum is mass multiplied by velocity, so …

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## Moments of Inertia & Spinning

Different types of moments of inertia can be better suited to different purposes and situations. If you wanted to store power in a spinning object, you could store more power in an object with a …

## Impulse and Momentum

Closely related to momentum is impulse (denoted by J), which is simply the initial momentum subtracted from the final momentum. The idea of impulse is important in things like mechanical engineering …

## Using Conservation of Energy for Motion Problems

In motion problems you can use the truth, but you can also sometimes use the principle of conservation of energy, and it is often simpler. In a closed system, energy will not be created or destroyed, …

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