Today’s Wonder of the Day was inspired by Evan. Evan Wonders, “how do you stick to a wall when something spins really really fast like the gravitron” Thanks for WONDERing with us, Evan!
Do you love amusement parks? Who doesn't, right? From the parking lot, you can see the bright lights and hear the shrieks of excitement. Once inside, your nose will quickly pick up the scent of all sorts of treats, such as corn dogs and funnel cakes.
The real fun starts once you get in line for a ride. Will it be a thrilling roller coaster? Perhaps you prefer the stomach-churning Tilt-A-Whirl? Others might enjoy the bumper cars or the Octopus.
If you're brave and don't mind defying the laws of physics, there's another ride that may beckon to you. It looks a bit like an alien spaceship. Once you step inside, you line up against the wall, your back pressed into a rubber pad.
As the ride begins to spin at a rate of 24 revolutions per minute, you feel yourself pressed into the wall. Suddenly, the floor drops away from your feet and there you are: stuck to the wall with nothing below your feet, seemingly defying gravity.
What is this magical ride? It's the Gravitron, of course! Depending upon where you live and what amusement park, carnival, or fair you go to, it may go by one of several other names, including Starship 2000, Starship 3000, Starship 4000, and Alien Abduction.
Riding the Gravitron may seem like pure fun, but there's a lot of science going on in its operation. To fully understand how the Gravitron works, you need to know some advanced physics. However, we'll take a look at a few of the basic forces at work.
As the ride speeds up, you feel yourself being pushed into the wall behind you, away from the center of the ride. This feeling you experience is called centrifugal force, but it's not actually a real force.
The experience of centrifugal force is actually the result of the combination of forces acting upon your body during the ride. The rotation and acceleration of the Gravitron would tend to push your body in a straight path off of the ride. Why doesn't that happen? The walls of the ride hold you in.
While it may seem like there's a force pushing you away from the center of the ride, the force actually working on you is the force of the wall pushing against you, keeping you from following your natural trajectory, which would be a straight path off the ride. This force is known as centripetal force, because it's directed toward the center of the ride.
So why don't you fall down when the floor of the Gravitron lowers? Does the ride defy gravity? Not quite! As the wall pushes on your body, your body pushes back against it. Newtown's Third Law of Motion holds that for every action there is an equal and opposite reaction.
As your body and the wall push against each other, the force of friction keeps you in place. While gravity is still present, the force of friction between your body and the wall can be equivalent to three times the force of gravity, thus preventing you from falling when the floor disappears below your feet!