When a roller coaster leaves the station, it begins moving toward the lift hill.  Have you ever noticed that most roller coaster stations are slanted in the direction of the track?   That is so that when the train is stopped on one of the brakes, it will start rolling again without having to go and give it a push.

   Some coasters use drive tires to move the train from one block to another, but you will also notice that the track on those coasters is mostly level in the braking fields. So, when the train leaves the station and goes up the lift hill, do you know how it is being pulled up the hill?   Right, a big lift chain pulls it up the hill.   Believe it or not, that lift chain is the only propulsion system that operates the coaster!  Ok, you ask, "but what happens when you get to the top of the hill and there is no more lift chain?"

   Well, that is the simple part.  In a word... Gravity.  You have to figure that an empty coaster train weighs somewhere between 9,000 and 15,000 pounds.  Think for a minute what would happen if you were to set a skate board on the top of a big hill and gave it a little shove.  Sure, that sucker wouldn't stop until it hit the bottom, right?  Ok, so now apply that same thought to a massive roller coaster train, which also has wheels on it. When the coaster train is carried to the top of the hill, and it passes the point where it begins to generate its own momentum because of the pull of gravity, then it quickly gains enough speed and force to thrust it through the rest of the track.

   Have you ever noticed how a roller coaster will seem to travel slower around the curves and faster down the hills?  Well, that's the reason why!  As the train is subject to the friction caused by the weight of the train pushing the wheels laterally against the track and the gravity pulling the other wheels downward into the track, the train begins to slow down.  That's why you have all of the ups and downs on a roller coaster.  If, after being slowed down by a sharp curve you didn't drop immediately down another hill in order to get back up to speed, then the whole train would simply stop.

   If you are one of the many kids or teachers across the country who are planning a science fair project about roller coasters, then you may want to use the ol' tennis ball model that everyone seems to like so much.  I have been asked many times about the best way to demonstrate the dynamics of a roller coaster by using a tennis ball on a home-made track, and that is why I wanted to give everyone the same information here.

Below you will see a rough drawing that I made for one teacher which shows a simple way to make a coaster track out of some coat hangers, styro-foam and tie-straps.  I will try to get a minute to make a better drawing for you in the near future, but until then, if you have any questions about how to make your model, then drop me an Email.   Good luck with your project and thanks for visiting CoasterQuest!