| Before we get lost in our exciting homeschool science | | | | Let me reveal the secret! Remember that the weight |
| experiments, let me teach you some things that air | | | | of air or air pressure at sea level is almost 15 pounds |
| pressure can do. The air around you has weight, and | | | | per square inch (psi). This force of 15 psi is actually |
| therefore it exerts a force on your skin and on | | | | pushing the cardboard upwards. Now the weight of |
| everything around you. This force is called air pressure. | | | | the water and air in the glass is pushing the cardboard |
| When the air pressure on an object is the same from | | | | downwards, but is too weak for the atmospheric |
| all sides, the object is stationary, but as soon as the air | | | | pressure of 15 psi. The cardboard piece cannot move |
| pressure changes a little, the object will move- making | | | | upwards, and therefore sticks to the rim of the glass. |
| it seem like magic. | | | | Now we move on to yet another exciting and |
| The cool breeze you enjoy at the beach is due to a | | | | mind-boggling homeschool science experiment, shall |
| difference in air pressure. When this difference in air | | | | we? |
| pressure gets greater, it can cause cyclones and | | | | The Ping Pong Ball that Won't Float: And you thought |
| tornadoes. In the following homeschool science | | | | only you could be stubborn; wait till you see the ping |
| experiments I will show you that air pressure can do | | | | pong ball in this experiment. Take a funnel with its |
| some things that are rather magical and contrary to | | | | broad mouth pointing upwards and place a ping pong |
| what you expect. | | | | ball in it. Your goal is to get under the funnel and blow |
| Upside Down Water Glass Trick: Fill a drinking glass | | | | upwards in order to make the ball float. Begin! What |
| with water till it is one-third full. Now place an index | | | | happened? |
| card or a cardboard on its mouth. Next, turn the glass | | | | Try again! Disappointed aren't you? The ping pong ball |
| upside down while holding the cardboard in place with | | | | won't float- exactly the opposite of what you thought. |
| your left hand. If you now release your hold on the | | | | How come? |
| piece of cardboard, what will happen? The obvious | | | | Here's the answer: When you blow air, it moves at a |
| answer that comes to our minds is that the cardboard | | | | high speed. Air moving at a high speed just wants to |
| will fall and the water will get spilled all over the place. | | | | rush by and does not bother to push objects in its |
| Now release your left hand, while still holding the glass | | | | path. Therefore there is low air pressure under the |
| upside down with your right hand. What happens? | | | | ping pong ball. The air pressure above the ball is- |
| Magic! The cardboard refuses to fall, holding the water | | | | you've guessed it right- 15 pounds per square inch. This |
| in the upside down glass- exactly opposite of what | | | | air pressure pushes the ball back into the funnel. |
| you thought! How did this happen? | | | | |