A Painless Science Lesson for Kids
The recipe for this experiment is simple:
1. Obtain one helium-filled balloon
2. Attach the balloon to a weight with about 40 feet of string.
3. Put the weighted balloon into the back seat of the family car.
4. Put the kids in the car.
5. Go for a ride, keeping the car windows closed.
Be sure that the balloon is floating freely in mid air in the back of the car. Have the kids watch it as you drive down the road. (Keep your eyes on the road.) As you accelerate, the balloon will sway forward in the car. When you brake, it will travel to the rear. In a right turn it will sway to the right, and in a left turn it will go to the left — exactly the opposite of what you would expect.
You have just proved that air has weight! We don’t realize that because we have been in the air all our lives, just as fish don’t know that water has weight because they float in it. What has happened here is that when the car moved in one direction, the air (being heavier than the helium-filled balloon) pushed past the balloon and moved it in the opposite direction. This has just the same effect as putting a tennis ball in a pail and filling the pail with water. The water (being heavier than the ball) goes below the ball and pushes it up.
Congratulations! You and your kids are now smarter than the neighbors and their kids!