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Gallery 7

# Free Fall

Experience the body’s natural fear response, as well as a very brief moment of weightlessness.

## How it works

This exhibit requires visitors to pass certain medical and physical checks before use.

Questacon staff will direct you to hang from a bar, then let go so you fall down the slide.

## Things to try or ask around the exhibit

Remember that it's okay to walk up the stairs and look down from the top of ‘Free Fall’, then walk back down the stairs if you change your mind. Saying 'no' to pressure from friends and relatives takes a lot of courage.

## Background

Adults and children both fall down the slide at the same speed. However, adults will hit the slide with greater force due to their greater mass and momentum, but they fall at the same speed. Questacon's Free Fall slide is approximately 6 metres high.

Normally, you feel you have weight, because as gravity pulls you downwards, the floor pushes up against your feet. While you are falling, there are no upward pushes on your body, so you feel as if you are weightless or there is no gravity (zero gravity). The weightlessness (zero gravity) that astronauts experience when orbiting the Earth is because they are constantly free falling around the Earth. The shape of the Free Fall slide lets a visitor fall (for a very brief moment) as if they were falling through space. The visitor’s overalls and body quickly come into contact with the slide, so they are slowed down by friction as well as the changing slope of the slide into a horizontal plane.

When you fall from a great height—say jump out of an aeroplane—the force of gravity is pulling you back down to Earth (actually, you’re being pulled towards the centre of the Earth, although you’ll only hit the ground). As you fall, your descent accelerates. For every second that you fall, your speed increases by 9.8 metres/second. So, we say that acceleration due to gravity (g) is 9.8 metres per second per second or 9.8 m/s2. Because the gravitational field of the Earth is pulling objects down, the mass of the objects themselves does not come into play. Factors like air resistance, however, can reduce this acceleration, depending on the falling body’s shape. For example, a sheet of paper feels an upwards force due to drag that significantly slows its rate of acceleration. But when that same sheet is crumpled into a ball, the effect of drag becomes almost negligible and it can fall with the same acceleration as heavier objects.

It is important to note, however, that the standard agreed value of 9.8m/s is itself approximate and varies at different locations on the Earth, due to the planet’s non-spherical shape. Some research suggests that in Sydney, g has a value of 9.797m/s2. This is because the distance from the centre of the Earth to Sydney is greater than at the poles (where g averages to 9.832m/s2) and shorter than at the equator (where g = 9.780m/s2). It stands that the gravitational pull is stronger the closer you are to the centre of mass. Effects due to the Earth’s rotation and orbital motion may also contribute.

## Finding the science in your world

Excited ‘Free Fall’ users who experience sweaty palms, shallow breathing and increased heart rate, have more adrenaline (or epinephrine) released into their bloodstream. This ‘fear response’ prepares the human body to escape or face up to a dangerous situation, either real or imagined. Humans are able to override their fears and many people really enjoy the fear response. Ask adrenaline junkies who enjoy extreme sports!