Beautiful Bernoulli!

Curriculum links:

• Physics – Forces and energy– Pushing, pulling, air movement
• Engineering – Magnus effect – How planes fly

Learning objectives:

1. Investigate how forces act on objects
2. Explore how objects may be moved by pushing and pulling
3. Explore how moving air can make things move

Materials:

• Hairdryer
• Ping-Pong ball
• Power
• Balloons
• Small coin
• Leaf Blower
• Light football

Safety:

• Be careful around leaf blowers.
• Do not do Malteser challenge indoors

Instructions:

Theory: 5mins

Explain to the children they are going to learn how things fly. Use a sheet of paper and ask them to predict what will happen if you blow along the top of it. It will rise up! This is because the air on top is moving faster and so has lower pressure than the air below, which causes the page to lift. This effect is what causes a plane to fly. Tell the children we are going to be flying something way more exciting than a plane…..a ping-pong ball! Make sure to ask them what shape it is (sphere) as recognizing 3D shapes is important in Maths.

Activity: 20mins

Take out the hairdryer and the ping-pong ball, hand them each to two different volunteers. Ask the children to switch it on and try and see if they can suspend the ball in the flow of air from the dyer. Explain that as air moves over a surface the lower the pressure that area has. The faster that air is moving the lower the pressure so if you have really fast air coming out of a hairdryer it traps the ping-pong ball in a kind of air pocket and keeps it there. You are even able to gently tilt the dryer from side to side whilst maintaining the ball in the air. The next level is to add a balloon with a coin in it into the flow. And an EVEN BIGGER challenge is to do the experiment with a leaf blower and football!

How it works:

Here we are introducing Bernoulli’s Principle, which 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. We demonstrate how we can use air pressure differences to lift things up. It may be a difficult concept for some children to grasp but is an exciting and engaging demonstration.

Send the children home with a chocolaty challenge!

Kids have to try to mimic the Ping-Pong ball and hair dryer by lying on their back on one of the benches with a Malteser on their lips. Their challenge is to blow the Malteser up into the air and catch it again in their mouth – success = prize.