We were dealing with big stuff for a four-year-old today! After our disk launchers from Kiwi Co introduced Travis to physics in a way even a preschooler could grasp, now we were talking about Newton’s laws of motion. Full disclosure: this required some review for mommy, who hasn’t touched this kind of material since college!
Here’s my quick recap: Newton’s third law of motion states that for every reaction, there is an equal and opposite reaction. So if the air from a balloon is escaping in one direction, the balloon will try and move forward in the opposite direction, making it spin, in this case.
Here’s how we set it up:
Slightly tug on a balloon and partially inflate it, just to loosen it up – don’t tie off. Now tape the balloon securely to the end of a straw (on the non-bendy side).
Travis immediately wanted to test out if he could blow up the balloon through the straw – neat!
Hold the straw on your fingers to identify the point where the straw balances. This is where you’ll insert a straight pin. Poke the pin all the way through the straw, then down into the eraser of a pencil.
Now blow up the balloon. Have your child hold the pencil, making sure their hand and arm won’t interfere with the motion of the balloon.
Let go and watch! The balloon will deflate, which causes it to spin around on the pin (Note: You may have to tug on the pin or spin the propeller by hand a few times to loosen things up enough).
We did this experiment over and over – a great visual of forces and energy, understandable even at the preschool level!