pool

This weekend I went swimming in a pool. I jumped in and with no surprise, I felt much lighter. This was due to the buoyant force. The volume of the displacement of pool water multiplied by the density of pool water and gravitational force was equal to the buoyant force. My weight minus the buoyant force was equal to my weight in the pool.
If I floated instead of sunk in the pool, then the buoyant force would be equal to my weight.

spoon levers

I was eating ice cream when I noticed that using a spoon required physics. The a scoop of frozen ice cream needed to be pried with force from a spoon. By using the side of the bowl as a fulcrum, I applied a downward force with my hand. Once there was enough force to overcome the static friction force of frozen ice cream, the small scoop was lifted. If I moved the handle of the spoon farther away from the fulcrum, it would have made lifting the ice cream easier since less force is necessary because the distance between the fulcrum and my hand increases and the distance between the fulcrum and the ice cream decreases. If the handle of the spoon is closer to the fulcrum it will be harder to lift the ice cream.

Dizzy

So I was sitting on my chair in front of the computer not knowing what to write about for this weeks journal entry. I began to spin in the rolling chair and I realized that that was actually physics. I stuck both of my feet out parrallel to the ground and although it was moving at the same angular velocity, their tangential velocity was more because the radius from my toe to the center of the chair was larger. I began to spin faster and faster. My toes now had a higher tangential acceleration but the same angular acceleration. I began to count in radians the number of spins that I could do. 2 pi, 4 pi, 6 pi, 8 pi, 10 pi, 12 pi . . .



no that is not fire. This is turning into a biology blog.

Jumping in Sand

Why is it harder to jump higher in sand than it is to jump on a court? This is the question I began to ponder as I grew exausted from playing beach volleyball. I then realized that Newton's Laws were the reason for my exaustion. In order to jump, the legs need to exert a force on the ground so that the ground exerts and equal and opposite force to push the body in to the air. In the gym, nearly all of the force exerted by the floor is transfered to the jump. On the beach however, tiny sand particles cushion the force of the jump by spreading outward. Therefore not a lot of the force is transfered to the jump because some force is needed to push the sand particles outward. The static friction of the sand is also relatively small compared to the solid, one-pieced court.

Halloween Humpty Dumpty

With Halloween coming up, unopened candy litters my house and so to tidy up the mess, I eat the candy. I ate some hershey's chocolate first and then some skittles. Finally I tried the M and M's and physics kicked in. When I was opening the bag of M and M's, all of the different colors fell to the floor. The impact caused many of the hard candy shell to break, sending small pieces in all different directions. The conservation of momentum tells me that the momentum of each M and M is the same as the momentum of the pieces that it broke into. The mass of the M and M multiplied by the velocity right before impact is equal to the sum of each shard's mass multiplied by its own velocity right after breaking.
Humpty Dumpty?

NASCAR

Over the weekend there were many intriguing football games to watch from high school, to college, to professional. There was even couple of baseball games that decided who would advance to the world series. What caught my eye, however, was what is often overlooked on Sunday mornings. Nascar aired for two and a half hours ( I didn't watch all of it, of course). While I was becoming dizzy because of the cars looping around in circles, I began to realize the physics that allowed the cars to move at such high velocities. Even if the cancellation of NASCAR would solve the problems with gas prices, I began to understand the thrill of the sport. All was going well until I saw in bright colors what friction looked like. Even though I know the fire wasn't fully caused because of only friction (like how cavemen started fires), friction against the wall as well as the force that it pushed back on the car with equal and opposite force made Terry Cook run from his burning truck. His high horsepowered engine allowed him to do maximum work in a little time. His truck could accelerate up to the highest velocities, which was good and bad in this case.

Da Ref

So I was at a volleyball game this week, cheering my heart out and forgetting about school when I remembered all about physics. The ball began bouncing back and forth with different kinetic energies, but that was not what I was interested in. The top referee stood above all in the gym and had a higher potential energy than if he was at any height lower. His mass multiplied by gravity and the height of the stand (about six feet) would represent his total potential energy. If he were to fall off of the stand (I wished), at the instant before he touches the ground, his kinetic energy would be equal to that of his potential energy (if there was no air resistance). While in mid air, his potential energy added to his kinectic energy would have been equal to his initial potential energy. Who knew that Newton's law of the conservation of energy exsisted in volleyball?