Free Fall

You don’t have to go into outer space to witness a microgravity environment - you just need to know how to work with gravity to get your way!

What You Need

• Water Bottle
• Water
• Bucket
• Pair of scissors
• Step-stool
• Help from an adult

What to Do

Use the scissors to poke a small hole on the side of the water bottle, closer to the bottom (this is where the help of an adult is important!). Once the hole is made, fill the water bottle three-quarters full with water and hold the bottle over the sink. What’s happening?

Now step outside or into an area that can get wet and place the bucket under the step stool. Top up the water bottle and put your finger over the hole. Step up onto the step stool and hold out the water bottle over the bucket. Take your finger off the hole and let the water bottle drop into the bucket. What happened during the drop? Did the bottle leak?

What's Going On?

When you hold the water bottle in the sink, the water flows out of the hole in the bottle. This is because of gravity; it’s pushing the water down towards the earth, so the water takes the easiest path: out of the hole!

But when you dropped the bottle into the bucket, the water didn’t leak out of the hole in the bottle! Isn’t there gravity here, also, that pushes the water towards the earth? Yes - there is - but the difference is that in this case, the water and the bottle are both falling to the earth. They’re falling at the same rate downward due to the Earth’s gravity, so the water doesn’t even have the chance to leak out of the hole. It’s already taking the easiest path towards the earth: straight down with the bottle!

Now imagine that you are standing on one of the water droplets in the bottle. When the bottle is sitting in the sink, you can feel that you are moving downwards with the force of gravity as the water leaks out of the bottle. But, when the bottle is dropped from a height above the bucket, you, the water, and the bottle, are all falling at the same rate. So from your point of view, you can’t feel the force of gravity. Inside the bottle, it’s as if you are as weightless just like in outer space!

Apply It!

Imagine that you’re in an elevator when the support cable has been cut, and it’s falling from the top of the building down to the bottom floor. You and the elevator are falling at the same rate, so from your point of view, there is no gravity and you are weightless!

Can you think of any other situations where you may feel weightlessness here on earth?  How about when you go over the top of a roller coaster hill - do the same principles apply?

- Aliya Merali