Amusement Parks A Playground of Inertia and Gravity

Did you know that the first "roller coaster" was an "ice slide"?  In Russia, the idea was formed and designed in the early 1700's.

Riders slid down these ice slides, some of them 70 feet tall and land in a pile of sand at the bottom. 

Wouldn't that be fun?  Apparently thousands of people thought the same and had the idea that maybe more people would enjoy the slide if they could ride on something?  So they made sleighs that slid down the ice slides. Then they thought, "why wait for winter!", designing a cart with wheels that could be used any time of the year.

Someone got really fancy after a time and designed a roller coaster that actually went upside down!

You know the rest of the story!  People will pay LOTS of money to have the thrill of their lifetime, flying across tracks, up and down, going faster than some cars do on the freeway!

Whew!  That was pretty fun to watch!  Knowing how inertia and gravity work together has helped humans understand how to control and enjoy some of this energy. 

The grandfathers of the roller coaster understood that energy can be used to keep things still and in motion.  An object waiting at the edge of the coaster is said to have "potential" energy.  Just like this sleeping cat:

We all know that if something scared that cat, it would jump into action.  Energy at sleep = potential energy or energy not used...it's there, it's just not being used.  As soon as the cat leaps to action the energy is called "kinetic" energy, or energy being used. 

The design of a roller coaster helps the cart keep moving, that's why there is one really TALL part of the coaster and the other hills are smaller, giving the cart time, or potential, to keep going. 

Potential energy or kinetic energy, it's all super exciting fun!