Ward's World Activity Guides

Page 2 + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com Find materials for this activity at wardsci.com. Discover more free activities at wardsworld.wardsci.com Magnus Flyers (continued) Step-by-Step Procedure: 1. 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. a. Place a little glue on the bottoms of the cups before you put the cups together. 2. Wrap a piece of tape around the bottoms of the cups to hold them together. a. You can decorate the cups with markers if you like. The decorations make it easier to see the spinning motion. 3. Take two rubber bands and loop one around the edge of a second, then back through itself. Pull to make the knot tight. a. Repeat to connect the other rubber bands to the chain. 4. Use your thumb to hold one end of the chain in the center of the cups. 5. Stretching the rubber bands, but not so tight they damage the cups, wrap the chain around the taped part of the cups while holding onto the end of the chain. 6. Once almost completely wrapped, hook the other end of the chain over your other thumb so that the chain is coming out under the cups. 7. To launch, hold the hand with the cups behind the other hand. a. Make sure the rubber band chain is coming out under the cups. 8. Aim your forward hand up in the air, pull the cups back (unwind a little if needed) and let go of the cups. It won't fly high, but rather glide gently to the ground. It is especially cool if you do it at the top of the stairs or off a balcony! Expected Results: Results may vary based on materials used, setup, procedure, and other factors, however, here are a few examples on what to expect: • When you release the launcher, the cups start to spin in the air. But if you look carefully the flyer is moving away from you but the cups are spinning towards you. This is called backspin. This backspin causes whirlpools of air behind the cups, which pushes the flier up and forward. In baseball, the Magnus Effect is used to throw curve balls but instead of topspin the pitcher adds a side spin, which causes the ball to turn (or curve) sideways. • During launch, the rubber band not only propels the cups forward, but also gives them a rapid backspin. As the backward- spinning cups fly through the air, a thin layer of air — called the boundary layer — gets dragged along for the ride and flung downward by the backspin. In accordance with Newton's Third Law of Motion, every action has an equal and opposite reaction: The downward force on the air results in an upward force on the cups. • This trick, known as the Magnus Effect, is well known to baseball pitchers. By varying the direction and rate of spin of a pitched ball, a pitcher can create a variety of wildly veering pitches: curve balls, fastballs, screwballs, and sliders. The stitches on a baseball add to the trickery; not just decorative, they assist in deflecting air sideways, increasing the deflecting effect of the spin.

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