Magnus Effect!

Curriculum links:

• Physics – Forces and pressure
• Engineering – How planes fly

Learning objectives:

1. Explore air pressure and dynamics
2. How to use physics in our everyday lives

Materials:

Experiment 1:

• Football
• Table tennis ball and bat

Experiment 2:

• 2 light cups e.g. paper cups, plastic cups or take-away coffee cups
• Tape
• Elastic bands
• Markers or stickers for decoration

Safety:

• To prevent anything from getting hit and broken during the experiment, do the experiment in an area with a lot of room – Maybe try it outside!
• In experiment 2, if launching the flyer from a height, only do this under adult supervision.

Instructions:

Activity 1:

Investigating the Magnus effect is great fun and there are lots of ways to explore it. You can find a ball and try kicking it on one side and seeing how it curls and then trying to kick it on the other side. You can also try it with table tennis bats and balls. It’s a lot of hands-on experimenting with the principle to see what happens right in front of you.

How it Works:

The Magnus Effect:

Whether its GAA or soccer, we often we see players standing over a free kick running up and then curving the ball into the net or over the bar normally just out of the goalkeepers reach. But how do they do that? It all has to do with spin and something call the Magnus effect!

When you kick a ball more on one side than the other (so not in the middle) it will spin as it travels through the air. So air is hitting the spinning ball as it travels. Now one side of the ball the air is moving in the opposite direction to the spin of the ball and on the other is moving in the same direction. This difference causes an area of high pressure and low pressure on opposite sides of the ball which in turn causes the ball to curl in the air

Second Experiment: Magnus Flyer

Step 1: Make the flyer

Put one cup on the table upside down and the other on top of the first, right side up, so that the bottoms of the cups are together. Make sure that the cup bottoms line up evenly with each other. Tape the bottoms of the cups together.

You can decorate the cups with markers or stickers if you like. The decorations make it easier to see the spinning motion.

Step 2: Make an elastic band chain

Take two elastic bands and loop one around the second and then back through itself. Pull to make the knot tight. Repeat to connect two other bands to the chain.

Use your thumb to hold one end of the chain in the centre of the cups. Stretching the elastic bands, wrap the chain around the taped part of the cups, while holding onto the end of the chain with your hand.

Step 3: Launch

Hook the end of the elastic chain over your thumb so that the chain is coming out under the cups and your other hand is holding the cups behind it. Aim your forward hand upwards, pull the cups back (unwind the bands a little if needed) and let go of the cups.

Step 4: Add height 

Launching the flyer is best done from a height – at the top of the stairs or standing on a chair.

How it Works:

The Magnus Effect:

As the cups spin through the air, the spinning action creates a whirlpool of air around them which exerts an upward force on the cups (the Magnus effect) causing them to glide.