Tennis

When hitting a tennis ball, have you ever wondered about momentum? The whole point of swinging as hard as you can is because of the law of conservation of momentum. In the inelastic collision of a tennis ball and the racket, momentum from the racket is transferred to the ball. The harder you swing, the more the ball can change in momentum. And because momentum is mass multiplied by velocity (and the mass only changes when you hit it so hard that you flatten the ball), velocity not only changes direction, but usually increases in magnitude. Not only that, but projectile motion, impulse after a bounce and much more all apply to tennis. Awesome!

Card Castle

Have you ever tried to make a castle out of ordinary playing cards, but they just seem to fall down all the time? It's hard for some people to simply stack two base cards, to form a triangle.
I found that making a card castle is surprisingly similar to physics. Stacking the cards on a tile floor is much harder then on a carpet because there is less static friction, and the cards slip too easily.
Also, in order two stacked cards to overcome gravity, they need to have equal and opposite forces on each other. And to do that, they need to have the same angle from the horizontal, but facing each other.
Then my card castle went higher then it ever did before. I was so happy that I named it Castel's Physics Castle!

Electricity

This week, I went with my mom on random errands that took forever. We were in the washing machine department for a long time, so I began to read the labels on each machine. I went from machine to machine and calculated that the average amount of electricity a washing machine uses for one load of laundry is 2.2 kilowatts.
This got me thinking: if you had an extremely large family... a sports family who uses multiple pairs of clothes a day and you did one load of laundry everyday, that would be 15.4 kilowatts per week, just for laundry. If you began to add up electricity for lights, refrigerators, ovens, TVs, computers, you begin to really pity Egor down at the power plant, lifting all those one Newton Weights one meter high.

Surfing

This week, I went surfing with a few of my friends. As soon as we got to the beach, we threw our boards into the water and paddled out. One of my friends could never ride a wave because she kept falling off the board. After a few attempts we got tired of laughing at her, so we all took a look at her board. Another one of my friends tried to take a wave on her board, but he fell off too. He paddled back out to us a told us the problem: she had forgotten to wax her board.
Without the wax, there is a very low static friction coefficient, making it very easy to slip and fall once the board is wet. By adding wax, the static friction coefficient becomes greater and it's easier to stay on the board without slipping!