Amusement Park Physics
Amusement park rides provide many examples of physics laws at work in the real world.
By Erin Bailey
A favorite summertime adventure for many families is a trip to the amusement park. Whether you like carousels or roller coasters, there seems to be something for every level of thrill-seeker. Amusement parks are also a great way to study physics in the classroom. When potential energy is converted to kinetic energy, the fun begins. Most rides rely on intricate engineering principles for their thrill-granting qualities and provide a great opportunity for students to study the effects.
Bumper cars are a bang-up way to observe all three of Newton’s laws of motion. Collisions are affected by velocity and the mass of the cars and drivers involved. Since bumper cars are essentially all the same mass, we need only to concentrate on the mass of the drivers. According to Newton’s Law of Acceleration, the greater an object’s mass, the harder it is to change its speed. In a bumper car arena, this means that heavier drivers will travel less on impact and lighter drivers will travel farther.
Newton’s Law of Inertia is also at work here. It states that an object in motion will stay in motion until acted upon by an external force. When two bumper cars collide, they stop. However, the drivers tend to keep moving in the direction and at the speed they were heading before the impact. This is why seat belts are so vital. Newton’s Law of Interaction explains why in a bumper car collision, the cars bounce off of each other in opposite directions. Both the object exerting the force and the object receiving the force have changes in acceleration.
- Eight marbles of the same size and mass (larger marbles work better)
- One marble of a different size and mass
- Two rulers that have a groove down the center
- Two text books of the same thickness
Procedure: On a level surface, line up all eight marbles in the groove of the ruler so they are touching each other. Have participants predict what will happen if one of the marbles is drawn back and pushed into the other seven. After learners have made their predictions, perform the demonstration. Repeat this several times, each time drawing back an additional marble to push into the remaining marbles.
The second part of this demonstration involves creating two ramps from the rulers and the books. Place the rulers facing one another, separated by 10 centimeters. Have students predict what will happen when two objects–moving in opposite directions–collide. Then place equal-sized marbles at the top of the ramps and release them. Repeat the demonstration using different-sized marbles to represent cars with different weight passengers. Another variation is to discover what happens when one marble is pushed down the ramp while the other is simply released.
Drop of Death
The gut-in-your-throat free fall was never my favorite ride. I hate the anticipation of the fall and the feeling in my stomach as the plummet begins. Inertia is responsible for that feeling and the accompanying sense of weightlessness. All objects free fall at exactly the same rate, regardless of their mass. In a free fall, gravity is the only force acting upon the objects. Thus, during the plummet, your body is falling toward the earth at exactly the same rate as the ride’s car. You are no longer pushing against the car nor is it pushing back on you.
- A plastic cup
Procedure: Ask students what will happen if you poke two holes on opposite sides of the cup. Then, drill or punch two holes about ¼ inch in diameter into the cup’s sides about an inch from the bottom. Fill the cup with water and observe as the water flows out from the holes. Fill the cup again, this time covering the holes with your fingers. Stand on a ladder or desk and drop the cup again. The water does not flow from the holes while in free fall because the water is falling at the same rate as the cup, and is not pushing against the cup.
Whether you love them or hate them, roller coasters are complicated models of physics laws. As the car climbs to the top of the first hill, an engine pulls it so that the car can build potential energy. But after it begins its free fall, the coaster completes the ride by switching between potential and kinetic energy. By completing the following activity, students will gain a solid understanding of potential and kinetic energy, as well as the effects of centripetal force, gravity, and friction.
- Foam pipe insulation cut in half (several yards for each group)
- One marble
Instruct your young engineers to build a roller coaster that includes the following:
- Two hills
- A complete loop
- A gap in the track
- A design that allows the marble to complete the entire track
Learners should sketch their design first, noting such things as the hill heights, the forces at work (centripetal, gravitational, and frictional), the diameter of the loop, and places where the coaster is building potential energy and using kinetic energy. After sketching, they will model their design with the foam insulation and marble and complete five timed runs. During the runs, students should note any places where the marble stops moving or nearly stops.
After assessing their design, your engineers should tweak their coaster, noting the changes on their sketches and completing five more timed runs. If time permits, you can change the design criteria and class members can use what they learned to build a better roller coaster.
It’s time to change the perception that physics is a five-headed monster with fangs. In reality, it is a branch of science that everyone experiences in daily life. Making the connection between the basic principles of physics and everyday events makes it more accessible and less intimidating.