## The Physics of Ice Skating - Isaac's First Law

Newton
figured out that if you know hard you push an object, and you know how
massive it is, you can figure out how fast its speed changes. Saying the
same thing, but using physics words: the force applied to an object equals
the mass of the object times the resulting acceleration. Writing this as
an equation, we say F = ma.

So if
we know the forces on an object, we then compute the acceleration, and
then we can then figure out how much its speed has changed.

The
ancient Greeks thought moving objects had a natural tendency to slow down.
Galileo and Newton, by experimenting, discovered that the reverse was true:
objects in motion will keep moving, uness acted upon by an outside force.
(This is also F = ma!)

If the
Greeks had invented ice skating, they would have figured this out! When
you push off on skates on clean ice, you'll glide for quite a while - the
blades slide over the ice with very little friction. Eventually, the frictional
forces will slow you to a halt. Too bad the Greek's lived in a temperate
climate!

**Back
to the Physics of Ice Skating**

by Karen Knierman and Jane Rigby