# Physics in the amusement park

## Summary

An amusement park is a large hands-on, body-on physics laboratory, full of accleration and rotation, free-falling bodies and vector additions. Newton's laws are experienced with eyes, hands and body. Simple toys that can be taken along on the rides are used to illustrate and measure the forces felt by the body and provide models of classical physics experiments, such as the Foucault pendulum and Galileo's and Eötvös' tests of the equivalence principle. Many of the investigations can also be adapted to the local playground.

## Newton in the amusement park

The first law obviuously applies to the girls waiting for the ascent the drop tower. They take along mugs with a little bit of water to examine the drop more closely. Newton's first law also applies during the slow ascent, even when you are high up, looking up and find that you have a l-o-n-g way to go.

Newton's first law applies when you sit for 7 seconds at the top, enjoying the view - waiting to be shot down.

... because nobody visits an amusement park to experience uniform rectilinear motion.

## Newton's second law

With Newtons second law, life becomes more interesting. In the Turbo Drop, the downward acceleration is 2g - twice as fast as free-fall. The heart stays behind. What happens to the water? Only gravity acts, so it cannot follow the mug, but looks as if it falls normally with 1g - but upwards! Don't hold the mug under your chin and don't choose a seat with wind from the front.

The ride can, of course also be studied using electronics - for a show or a qualitative experience, a slinky gives a stronger visual effect of vertical acceleration.

## Two-dimensional motion

To study horizontal acceleration, a little cuddliy animal in a string works fine, combined with a protractor. You see how the rabbit falls behind as a I start moving. 10 degrees corresponds to an acceleration from zero to 50km/h in 8 seconds.

Most accelerations in an amusement park are much larger - like in the "wave swinger".

As you see the wave swinger start, take a moment to consider which swing will hang out the most - an empty swing or a heavily loaded one. Stay and watch - as all swings in the same circle hang out in the same angle. The equivalence principle in front of your eyes. Recall Eötvös who used the earth as a giant wave swinger, testing the equivalence principle!

## Foucault

How can we know that the earth rotates? Because we have night and day? People have known that long before they know the earth was rotating. The critical experiment is, of course, Foucault's pendulum in Pantheon in Paris. A miniature Foucault pendulum can be used to find out if it is the platform or the ground that moves, as you finish the river rapids ride.

## Roller coaster

What is an amusement park without a roller coaster, where we need three dimensions to describe the motion. In Liseberg, the natural hills and valleys are used and the track is designed especially to fit in. To work out the forces, we need to know the altitude relative to the highest point, the slope along the track and sideways, as well as the curvature sideways and up/down. So every part of the track is numbered and has these parameters well-defined.

Take your rabbit-on-a-string along to find out at what parts of the track you are weightless, and how the rabbit moves along the curves and down the slopes. Does it matter what seat you choose?

## Point particles

In an amusement park, the approximation of a point particle becomes obviously irrelevant. Your body will certainly know the difference between a circular motion where you head stays upright, and one where it doesn't. What happens to your blood in this attraction?

## What happens in a loop?

And what happens as your body experiences rotations around various axes? What is up? What is down? An amusement park is a large laboratory, ready to use!

When you do physics in an amusement park, you are in good company - Einstein gave a talk in Liseberg in 1923.