Blog Entries posted by CoreyK
I am hard at studying and then my brain starts to wander and before I know it I am on YouTube; the site that can cause any determined student to suddenly lose all concentration. And then somehow through the incredible maze of related videos I find myself at a video showing how to win a pinewood derby race with science. Little did I know that it would serve as review with plentiful information on the conservation of energy and also how both Potential and Kinetic energy affect the car. The video goes to show how potential energy, which is dependent mostly of height, is transferred into kinetic energy as it travels down the track and gains speed. It also shows how some of the potential energy is transferred into heat energy through friction. It then explains how to make the fastest car you want to start with the most potential energy and get the most of that energy transferred into kinetic energy, which is dependent mostly on velocity. To maximize potential energy the weight is placed toward the top of the car. To reduce the amount of energy lost the car rides on three wheels instead of four.
So I'm sitting here, pushing down on keys, listening to music and all of this is physics.
Both sitting and typing are examples of newton's third law, all forces come in pairs. My fingers are hitting the keys just as hard as the keys are hitting my fingers and my butt is pushing down on the chair just as hard as the chair is pushing back on me. (Fn=Mg)
Now the music is not Newton's third law, it has to do with sound waves and how the vibrations from the headphones travel through the air and are received by my ear drums and processed and understood as sounds by my brain.
I go to take a nap. I think, â€œThis weekâ€™s is over. I made it through! I deserve this nap!â€ But, no. This week has one final blow to deal. Physics blogs. So I meander my way to a computer sit down and begin questioning how I am going to complete this in time. The stress builds and I feel my body heating up with anxiety and a sweat starting. Right as I am about to write about â€œDeflate Gateâ€ and continue beating the dead horse of a subject this has become I realize; I AM PHYSICS. The heat! Itâ€™s internal energy. The sweat! Itâ€™s heat transfer. All of these things are physics!
Now letâ€™s explain. The heat created from my body is the energy of reactions inside of my body giving off heat. And the sweat this is helping with heat transfer, the water in my skin is increasing the surface are so the cooler air around me can more easily take away the heat from my body, getting me down to a more comfortable temperature.
Wellâ€¦ we triedâ€¦.
These three words were the resignating theme at the end of an 8 hour day of sawing, screwing, welding and re building our catapult. At hour seven we decided that we need to make a lock for the monstrous contraption. A hand full of welds later and a spark or two down then sleeve it was all set up, ready to test and even more ready to say it was finished. The weights were set, the bar pushed up, and the pin holding it in place.
It was marvelous, the seven hours of work was all worth it. With one tug on this rope the pin would come out and are creation would come to life. Yeahâ€¦ no. Now quite.
The weight on the arm pushed down too much on the whole that the pin was put into, so no matter how hard we pulled it just would not come out. Friction was the answer! So much weight pushing down on the pin from the wood hole that the surface area holding the pin down because of the weight exceeded the force we could apply to pull the pin out of the hole.
So back before I injured my knee I used to play hockey. I loved the sport and I was pretty good at it, nothing great but pretty good. I did however have quite the slap shot. At a camp they measured how fast using a speedometer. It clocked in at 86 miles per hour, which wasnâ€™t too shabby for being in 8th grade. Now letâ€™s find the acceleration of the puck.
Saying that the puck stays flat on the ice for the whole distance (20m) traveled and neglecting friction and saying it takes 3 seconds to reach the net we know:
Vf: 86 mph or 38.4 m/s
T: 3 s
We can use the equation:
The slap shot encompasses many parts of physics; the stick has potential energy as it flexes back as well as kinetic energy from being swung forward, the mass of the player helping accelerate the puck in a quicker time.
Watch this video and come back!
Back? Okay cool!
So i thought this was interesting by not only disproving some myths but showing some good scalars and vectors in the cane showing forces and the direction of the forces.
It also showed some magnetism with water and ions ect ect....
Okay here's what we're going to do for a second or two. Lets turn off friction.
Now if we could just turn off friction without destroying the particles and atoms pushing against one another it could be fun for a minute or two- barring no one was driving, we would all be unable to walk, stand, grab objects, drive, start cars, ect, ect. you get the idea. The reality of this though is that by deleting friction we ultimately have to stop atoms from repelling and being attracted to one another and this is a very sticky situation, actually is very very slippery. Dirt piles would turn to liquid like and the ground would be like quicksand. life would be very hard to say the least.
So after experiencing the full force of physics during football practice and tearing my MCL I was lined up for another run with physics.
Now everyone knows that feeling when an elevator starts to go upwards you feel pushed into the ground and as it goes down you feel like you're being lifted off the ground. Well there's your physics. Now lets explain...
As the elevator begins to move upwards the inertia of the person standing there wants to stay stationary so the normal force (Fn) exerted on the person standing must be increased; creating the feeling of being pushed into the ground. That's why if you were to take a bathroom scale into an elevator and stand on it as it goes up you would appear to be heavier, because scales don't really measure weight they measure the force of gravity(Mg) against the scale. The reverse of this is what happens when the elevator goes down, the normal force would decrease because the inertia of a persons body would prefer to stay stationary.
So after being one of the outside forces to stop a persons (objects) motion I was exposed to even more physics with having to use the elevator.