Physics of toys- Cup Flyers // Homemade Science with Bruce Yeany
4 Video Views·Oct 24, 2015
Plastic, foam or paper cups can easily be made into indoor flying objects that demonstrate the force that causes curveballs, golf balls and many other examples to curve due to the Magnus effect. A variety of sizes and variables can can this simple experiment into a fun and educational learning experience.
Hello, I'm Bruce Shaney and today I'm going to show an application of Bernoulli's principle called the Magnus effect.
Now, it's a simple demonstration and it can also be a lot of fun.
So, let's take a closer look.
Now, these flyers can be made out of all sorts of materials.
These are cups and bowls that are made out of foam.
Now, let's go see how it's put together.
The construction is very simple.
Take the cups and put them bottom to bottom
and a piece of tape is going to hold them tightly against each other.
Let's get this wrapped around here
and press it down tight so they hold
and there we go.
And we did that with the plastic ones and also with the paper.
Now, I start with four small rubber bands and simply loop them together.
So, there's two
and there's a third one
and we'll add one more.
So, here's my long single rubber band.
For my bigger pieces, I use large rubber bands
and this one I use for my very largest piece.
Now, let's go try it.
We start by holding the rubber band in the center of the cups,
wind it around three or four times,
stretch it out in front,
pull it back and release.
Now, let's try that again.
Now, we also have a variety of plastic cups to choose from.
These small cups work really well.
Now, we have a variety of paper cups.
Let's go try a couple of these.
Now, this largest one is made from two popcorn barrels.
Let's go see how it flies.
Pull it back and release it.
So, the question is, what actually causes this magnus effect?
Now, the rubber band is wrapped around the cups,
it's stretched back,
and when I release it, the cups go forward
and as it travels forward, the cups are actually spinning in this direction.
Now, to see this a little bit better, I put an LED light inside this cup.
Now, let's shoot it.
Now, using the long exposure of the camera,
we can see the trail of the cup moving upward
and also that it's spinning at the same time.
Now, with a little investigation,
you can find out how this movement causes an object to curve.
Now, what do you think would happen if we wound the rubber bands in the opposite direction?
So, the cups are now going to spin this way as they travel forward.
Let's try it and see.
So, now the cup curves downward.
Now, we can also try changing the orientation of the cup
so now that it's vertical instead of horizontal
and see what effect that has.
This causes the cup to curve sideways.
Now, I do want my students to try this for themselves,
but in that case, we use these foam cups
simply because they have a shorter flight path.
So, I found the flying cups to be a good activity for students to investigate.
There are several variables that they can change
and they will see how they affect its flight path.
Now, I gave myself a challenge
and that was to build a holder that would keep the cup in place
until I'm ready to fire it.
So, I call this my cup gun.
The rubber band is wrapped and stretched the same way,
only it's this wooden piece that's holding it in place
rather than in my hand.
Pull the trigger.