Magnus Sports
- Physics
- Pressure, Magnus Force
- Grade Range
- Middle School, High School
- Format
- Hands-on
Materials
- Paper tube
- Tennis ball
- Wiffle ball
- Wood plank
Safety Precautions
Please see the Other Hazards and Safety Precautions section on the Demonstration Safety page.
Demonstration
- Hold the wood plank at an angle, perpendicular to the audience and above the ground. Roll the tennis ball down it, and allow it to bounce away, to show the direction of movement.
- Ask the audience if a paper tube should move in a similar way. After taking some answers, roll the paper tube down the plank. When it falls off the plank, it will move in the opposite direction!
- Show the tennis ball to the audience, and choose a volunteer. Toss the tennis ball to the volunteer, and have them throw it back.
- Show the Wiffle ball, and toss it to the volunteer. After the first toss, throw it with a spin, and watch as it moves around in the air!
Why This Works
The Magnus Force is an effect that we see on spinning objects as they move through a fluid, such as air. The best way to explain this is to think of a baseball being thrown, but it has a clockwise spin on it. As the ball travels forward, it is running into the air around it. But, because of the clockwise spin we put on the ball, the left side of the ball is spinning towards the batter, and the right side is spinning away from the batter. This forward motion on the left side of the ball runs into slightly more air, which means the left side of the ball experiences slightly higher air pressure. The right side of the ball runs into slightly less air, and experiences slightly lower air pressure. The difference between these two points is enough to make the ball curve towards the low pressure side, resulting in a curve ball that moves to the right!
Additional Information
- This effect can be seen in many sports, such as baseball and soccer!
- This is a good demonstration for showing students how science plays a part in everything we do, including sports!
- This demonstration is a part of the Pressure Show