My eldest daughter found a book I bought on Force and Motion for K-2nd graders, and she decided she wanted to do an experiment. We haven’t done one in a long while, so I decided it was time. I also decided it’s not really all that hard to come up with 5 minute science experiments using common household materials.
So, with that in mind, we decided to do a basic experiment with gravity. We selected different materials: a small stone, a small pom-pom, a large pom-pom, a small eraser, a piece of construction paper, a piece of mulberry paper (since I didn’t have a feather, I thought this was just as good), and a crumpled up piece of paper.
We talked a bit about gravity being the force that keeps us on the ground and that it is the force at work when things fall. So we just decided to test what kinds of materials landed on the ground faster than others.
We pitted these things against each other:
mulberry paper and rock
mulberry paper and crumpled paper
mulberry paper and construction paper
eraser and paper
large pom pom vs small pom pom
stone vs eraser
My daughter made her guesses, then we checked by having her stand on a chair and letting them go.
mulberry paper and rock; her guess = rock; result = rock.
mulberry paper and crumpled paper; her guess = mulberry paper; result = crumpled paper
mulberry paper and construction paper; her guess = construction paper; result = construction paper
eraser and mulberry paper; her guess = mulberry paper; result = eraser
large pom-pom vs small pom-pom; her guess = large pom-pom; result = they landed at the same time.
stone vs eraser; her guess = at the same time; result = at the same time.
So what did we learn?
Things that looked like they were bigger didn’t mean they fell faster. The two different sized pom-poms landed at the same time, so did the rock and the eraser. The two flat pieces of paper (construction and mulberry) landed at different times – the lighter mulberry paper simply floated down slowly.
We talked about how gravity can’t be seen, but it is a force that causes things to fall down or be pulled toward earth.
We talked about how we can use our muscles to overcome the force of gravity briefly by jumping. But because of gravity, we always fall back to the ground. We also talked about how animals overcome gravity by special tricks: birds use their wings to fly, some frogs have special feet to help them stick to trees, grasshoppers hop, and other animals (like monkeys, koala bears, and sloths) climb.
Other questions to ask are:
How does gravity help you on a slide?
Why don’t you float away when jumping on a trampoline or a diving board?
What is harder, walking up a hill or down a hill and why?