Montshire Minute: Amusement Park Science

Originally aired during the week of March 12, 2000

Monday

Quick, what's your favorite amusement park ride? Lots of people would answer the "roller coaster." The roller coaster needs an engine to pull it up to the top of the first crest. After that, the coaster dips and rises all on its own. At rest, the roller coaster represents potential energy. Teetering at the top of the first hill, it may not be moving at all. But give it a push over the brink, and all that potential energy is transformed into kinetic energy. And you're on your way! The law of conservation of energy says that energy can't be created or destroyed. So all roller coaster tracks must start at a high enough elevation to finish the course. Of course, it helps to be able to come to a complete stop, too, so coasters are equipped with special compressed air brakes. You can create your own coaster at Montshire's new exhibit Amusement Park Science!

Tuesday

Playing with bumper cars at the amusement park may be the best cure for road rage! It's also a great example of Newton's third law of motion. It's the law that says "thou shalt not... " oops, sorry. Wrong list. It's the law that says "to every action there is an equal and opposite reaction." Even when we're standing still, we exert a force on the floor. This is opposed by the upward force the floor exerts upon us. If you pull on a spring, the spring pulls back on you. In bumper cars, if a driver exerts a force on a second driver, the second driver exerts a force equal in degree and opposite in direction to the first driver. That's one of the reasons you feel a jolt when you collide. In head-on collisions, size also matters. A bumper car driver with less mass will experience a bigger jolt when colliding with a driver with greater mass. So go ahead and bang away - its fun, and you're obeying the law - Newton's law!

Wednesday

We tend to think of inertia it as the thing that makes it hard for us to get out of bed in the morning. Sir Isaac Newton defined inertia as the tendency for objects to resist change in motion. Throw your clothes into a pile on the floor, and the clothes will still be there until someone deecides to pick them up. The opposite is also true: objects that are in motion tend to stay in motion, unless some other force intervenes. These two observations are considered part of Newton's first law. But wait a minute. Everyone knows that a ball rolled forward along the ground won't keep moving forever. What was Sir Isaac talking about? There are forces in nature that will interfere with motion, and one of these forces is friction. Friction slows things down. It happens when you scuff your shoes against the floor, or when the tires of your car meet the road. Or when the brakes of the roller coaster are applied!

Thursday

If you're a thrill seeker, no doubt you're the first in line for the tilt-a-whirl at the amusement park. You know, its that big round machine that turns around, faster and faster and faster, until you feel like a piece of wet laundry pinned to the inside of a washing machine set on the spin cycle. Ugh... I get dizzy just thinking about it. Imagine tying a length of string to a stone and whirling it around above your head. It's really the force exerted by your hand tugging on the string that keeps the object moving in a curved path. Well, this inner pull is called centripetal force, and it's the same force that presses us up against the inside wall of the tilt-a-whirl. Now imagine that you're letting go of the string. The outward pull (or centrifugal force) causes the stone to fly off in a straight line. You can play around with these forces at Montshire's new exhibit Amusement Park Science.

Friday

Here's a real "open ended" science puzzler. You'll need Styrofoam, paper, or plastic cups of different sizes and shapes, and a few marbles of different size. First, use scissors to cut out the bottom of each of the cups. Your mission: pick up a marble with a cup without touching the marble with your hands, without blowing on the marble, or without using the cup as a "scoop." (Hint: think about how the "spin cycle" works in your washing machine). Try using different sized cups and different marbles. Does the size or slant of the inside of the cup make a difference in how easily you can "pick up" the marble? Does the size or weight of the marble make a difference? When an object spins around, it creates centripetal force, a force that pulls it outward. This force is used in the "tilt a whirl" ride at the fairgrounds, and in your clothes dryer at home!