At-Home STEM Activities: Water Freefall
In today’s Distance Learning Module, we explored the idea of microgravity and learned that scientists simulate this environment on Earth to help astronauts train for spacewalks. Follow up to the lesson with this all-ages activity, in which we create a “weightless” freefall with a cup of water. (Best performed outdoors—this will be messy!)
Background
If you read today’s Distance Learning Module, you’ll recall that astronauts in space do not experience true “zero gravity,” as they orbit at a distance well within the influence of Earth’s gravitational field. However, when a spacecraft is moving at the same speed that it is “falling” toward Earth, the people inside the ship enter a state called freefall. They float in the air. Since they are not in physical contact with the ground, it feels to the astronauts as though their bodies have no weight.
We used two examples in the Distance Learning Module to think about freefall: the experience of going over a hump on a roller coaster, and a person standing in an elevator with a broken cable. The activity below is a hands-on option to demonstrate the same concept.
ASTRONAUTS SHANE KIMBROUGH AND SANDY MAGNUS PLAY WITH FLOATING FOOD DURING THE STS-126 SHUTTLE MISSION (IMAGE CREDIT: NASA)
Materials
Disposable (paper/plastic/foam) cup
Sharp pencil
Water
Procedure
Set up in an outside area, or somewhere that it’s okay to spill water on the ground
Use the pencil to poke two holes on opposite sides of the cup, about an inch from the bottom
Fill the cup with water, holding the holes closed with your fingers (this may require adult coordination, with younger learners watching)
When you remove one or both of your fingers, gravity will cause water to flow out of the holes in the cup, as seen here.
Now cover the holes with your fingers again, and re-fill the cup with water
Hold the cup at arm’s length, and remove your fingers from the holes, so that water begins to flow out
Let go of the cup, allowing it to fall straight downward. Watch what happens to the flow of water! (We found it helpful to record this step in slow-motion, so we could get a really good look at what was happening—see below.)
What’s happening?
You should observe that as the cup falls, the water stops flowing through the holes. This is because the water and the cup are moving at the same speed: the water is suspended in freefall inside the cup. In this way, the water in the cup acts like an astronaut in a low-gravity spacecraft environment!