Foams are everywhere from the cosmos to your cappuccino.

Bubbles and foams are everywhere—from soap bubbles to sponges. Foams are mostly air, about 90 percent air, and when air is mixed with liquid to form a foam, together they act like a solid. Try it out for yourself. Push on some bubbles next time you are washing the dishes, they will move with force, but not on their own like a liquid would.

Here is a little bubble secret. Bubbles can help you from spilling your drink. Recently researchers have found that beverages that have 5 layers of bubbles on the top will be less likely to spill than a liquid without bubbles. This means that a latte will not spill when you walk, while hot coffee without bubbles will spill. Ouch. If you are commuting and want coffee, order a coffee with a bit of foam on the top and spare your epidermis.

So what are the bubbles doing? Well, the bubbles push against each other and the friction between the bubbles eats up the energy of the sloshing. The liquid with bubbles on top will not come out of the cup when you are walking. So, a soda with lots of bubbles does a better job of not spilling than a flat soda.

See for yourself in this short video:

http://gfm.aps.org/meetings/dfd-2014/5416599269702d585c690100

Ice Cream and Pudding and Bread, Oh My

The world is full of solid foams too, that is, foams that combine air with a solid. There are many that are quite yummy. Ice cream, pudding, and bread, are all solid foams. The bubbles give these foods mouth-feel, which is what makes them so pleasing.

But, there are more serious uses of foams. Scientists wanted to catch a bit of comet dust, which holds secrets about the formation of our solar system. It ends up that comets fly really fast (like 40 times a bullet) and catching dust particles in a cup would not work, because both the cup and the dust particle would be destroyed. What was needed was a way to capture comet dust that would not hurt the dust. So, scientists use a special foam, called an aerogel, which is 99.8 percent air with the rest being glass. As the particle enters the aerogel, small glass fibers are broken, which slow down the comet particle without hurting it. From these particles we can learn more about comets and our solar system.

What will bubble up from these findings is uncertain, what is clear however is that the uses of bubbles and foams are unlimited and even cosmic.

References:

Universal Foam 2.0 by Sidney Perkowitz (Affiliate Link)

NFL great Jerry Rice found the football flies in a way that perplexes rocket scientists.

A football has a shape that mathematicians call a prolate spheroid. While that sounds like a weird word, prolate spheroid shapes happen in your everyday life as grapes, lemons, and watermelons. They are all longer in one direction than the other. This weird shape of the football means that it cannot be thrown like a baseball. The only way for a football to stably travel long distances is if thrown with a spin.

When a quarterback throws a football, the football spins more than 600 times in a minute, which is as fast as a CD spinning in a CD player. This spin does a few things. First, it stabilizes the ball. Without the spin, the ball would flop over. The second thing that the spin does is it creates new complicated behaviors too.

The spin creates what scientists called gyroscopic torque. This sounds like a strange thing, but gyroscopic torque happens when you ride a bike. When the wheels spin, you keep upright. However, as soon as the wheels slow down, you lose your balance. The same happens with the football. The spin keeps the football’s nose from falling down just like the wheels of the bike.

However, the spin also allows footballs to do something a bit strange. It acts like a toy gyroscope. If you ever take a spinning gyroscope toy and push it, the toy will mysteriously move on its own in another direction. This same thing happens to a football. A football spins and points its nose up, but gravity pushes its nose down as the football comes back to earth. So the football moves on its own and points sideways. (Next time you are watching a game, notice that the football’s nose is a bit to the side. That’s gyroscopic torque in action!)

So why is this a big deal? If a football is pointing sideways, then this means that a ball can be off its target by a few yards. Quarterbacks must account for this shift when they throw. Many QBs know about this instinctively and do this automatically. But, new QBs have to learn this.

Interestingly, a football spins differently if a quarterback is right-handed or left- handed. When a right-handed quarterback throws the ball, the ball spins clockwise. This means that the ball shifts a bit to the right. A left-handed quarterback throws the ball with a counter-clockwise spin, so the ball veers to the left. A ball will look very different to a wide receiver depending if a quarterback is right handed or left-handed. In fact, Jerry Rice, the great NFL wide receiver, confirmed that the ball looks different. Rice saw something that perplexed professors for years.

As one can see, the football’s tight spiral is poetry in motion, but it is also science in action.

 

Next Generation Science Standard NGSS PS2.C

Reference books

The Physics of Football by Timothy Gay (Affiliate Link)

Newton’s Football by St. John and Ramirez (Affiliate Link)