Editing Magnus Sports

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Physics]]:
| Pressure, Magnus Force
|-
| Grade Range:
| [[Middle School]], [[High School]]
|-
| Format:
| [[Hands-on]], [[Stage]]
|}

The Magnus Force is an effect that we don't think about, but we have seen or experienced. This demonstration connects well with students who have played sports such as baseball, soccer, and softball!

== Materials ==

* Paper tube
* Tennis ball
* Wiffle ball
* Wood plank

== Safety Precautions ==
Please see the Physical Demonstrations section on the [[Demonstration Safety]] page before performing this demonstration.

== Demonstration ==
;Presentation (Stage):
# 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!

;Presentation (Hands-on):
# Set out the objects, and prop the board up so the tennis ball and paper tube can be rolled off the side of the table. Be sure to secure a space where you can throw a ball back and forth.
# As students come up, have them try rolling the tennis ball down the slope, followed by the paper tube. If you have students who are willing, throw the different balls back and forth with them so they can see the wiffle ball changing direction 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 with a clockwise spin on it. As the ball travels forward, it is running into the air in front of it. But, because of the clockwise spin we put on the ball, the left side of the ball is spinning ''towards'' the direction of motion, and the right side is spinning ''away'' from the direction of motion. The 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 therefore experiences ''slightly lower'' air pressure. The difference between these two levels of pressure is enough to make the ball curve towards the low pressure side, resulting in a curve ball that moves to the right!

We see this effect happen with the paper tube as it rolls off the slope as well. Once the paper tube is in free fall, the top of the tube is spinning ''towards'' the direction of motion, while the bottom is spinning ''away'' from the direction of motion. This means the top and front experience ''slightly higher'' pressure, and the bottom and back experience ''slightly lower'' pressure, which makes the tube travel backwards while in free fall! However, we don't see this happen with the tennis ball when it rolls off the board. This is because this effect is dependent on how massive the object is. A tennis ball is much heavier than a single piece of paper, and it is also heavier than a wiffle ball, which is why we don't see this effect happening to the tennis ball. But if we were to throw the tennis ball a farther distance, then we could see it start to curve if it has a spin to it!

== 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]]