This Hub Lab sees Phil talking about the Bernoulli principle again, and he shows us how it works with water and with air!
We have looked at Bernoulli principle before. It states that if the velocity of a fluid increases, the pressure decreases.
We can see this with the wings of airplanes, the sloped shape allows the air above the wing moves faster than the air below, meaning there is lower air pressure above the wings, causing the aircraft to be pushed upwards by the higher pressure below.
Now we are going to take a closer look at Bernoulli's principle! If we take a funnel and run a flow of water through it, we can actually trap a ping pong ball in the stream.
The water is moving faster around the ball, creating an area lower pressure, the higher pressure beneath the ball then pushes upwards and holds the ball in the funnel!
Procedure: Get the tube and attach it between the tap and the funnel, when you hold the ping pong ball in the funnel (facing down) before you turn the tap on it will just fall out. But when we turn the tap on, the ball stays!
The running water is moving faster than the air and therefore has a lower pressure. The air has a higher pressure so pushes up against the ball and keeps it in place.
Next, get yourself a big plastic bag. See how much you can blow it up in 10 seconds, it probably won't be a lot.
Let’s use Bernoulli’s principle to our advantage!
Hold the end of the bag open and blow in a burst of air, quickly squeeze close the end of the bag. You will notice it is far more inflated than when you tried blowing into it for 10 seconds!
This is because the one breath you blew in created an area of low pressure that helped suck extra air from the room in as it travelled. Try and think of some examples of where else we could use this!
Download the activity sheet and full lesson to share here!