Ten Favorite Things about Physics

One: Inertia

 My favorite concept is Inertia. Inertia is NewtonsTthird Law which states that any object, whether in motion or at rest, will continue doing what it is doing. I thought this was amazing because I thought everything just started at a rest state where there not going and that when we push something we apply energy to the object making it move. I thought that this energy would be used up (in the form of heat) and when it ran out of energy it would stop. But mass doesn't act like a car, instead it's outside forces that do the stopping and starting 

Two: Newton's Second Law of Motion. 

Newtons second Law explicitly states that an object's acceleration is directly proportional to the net force acting on it and indirectly proportional to the mass. I really like this mainly because it was one of the simplest and easiest examples to understand in physics. It makes sense that the more force you put on an object the more it will accelerate (or "decelerate" due to an opposite force). And it also makes sense that the more mass something has the harder it will be to push it. It's much easier to push a small child than a large man. 

Three: Newton's Their Law of Motion 

This concept blows my mind, but makes tons of sense at the same time. Newtons Third Law states that to every action there is an opposite and equal reaction. No wonder I don't just break through a chair when I sit on it, because it pushes back on me (I guess the creaking noise when a large person sits in a chair is the chair actually pushing back).It would also be nice to say that if I hit someone then that person hit me also and the ensuing fight is just as much his fault (though that wouldn't get passed the headmaster). I guess thats why I would have bloody knuckles after the fight, because my opponent was hitting me right back.

Four: Systems 

Another smaller concept that I really like is that a force acting inside of a system doesn't do anything to the system. Only an external force can cause something to move or slow down. A person can't stop him or herself from falling through the air without a parachute and we also need to push on the floor in order to move. 

Five: Tangential vs Rotational 

Tangential velocity is the linear velocity (how fast a spot on a wheel is moving at any point) and rotational velocity is how many rotations a circular object takes. I thought it was especially interesting that a point on the outer part a circle has to move faster (have a higher tangential velocity) In order to keep up with a point closer to the center of a circle. It's just strange thinking one part of an object is moving faster than the other. 

Five: Lever Arm

In a way I always knew, but never realized, that the longer something is the easier it will be to move something else with it. Working with my Dad on projects at home we would always use a longer wrench for more stubborn bolts but I never actually thought about why that made things easier. Because the work formula is W=F times Lever arm the longer lever arm you have the smaller the force if you want to do the same amount of work. "Physics makes good sense" (Paul G. Hewitt).

Six: Centrifugal Force. 

First centrifugal force isn't real, it is merely the name we give to the inertia of us wanting to stay going in one direction while a centripetal force pushes us closer to the center of a circle. I thought that was really cool because I have felt the force of a car pushing against me as I go around a turn. Now when I sit in a car I actually know why my body hits the car door.

Seven: Gravity 

At every moment we are being pulled down towards Earths core and if it wasn't for Newtons Third Law we'd all be screwed and fall straight towards the center of the Earth. This is do to the fact that  every single object (that has mass) attracts other objects. and so we are attracted toward the center of earth. So if a girl says she doesn't find me attractive, i'll know physics says otherwise. 

Eight: Satellite Motion

Thanks to a combination of gravity and inertia we have satellites. If an object is moving fast enough around earth than it will not fall towards earth because it's inertia will keep it going in a linear path, but if it is close enough than gravity will still have an effect causing that linear path to turn and curve around the earth. So in reality satellites (and astronauts) are all in free fall and inertia is the only thing keeping them safe.

Nine: Magnets 

Magnets are amazing. The thought that some invisible force can actually interact and pull or push a force. I thinks it's really cool how magnets repel each other. Because field lines move from north to south (outside the magnet) and south to north inside if you put a south to a south or a north to a north the field lines oppose each other and actually push each other away. But if a North and South are in close proximity their field lines are going in the same direction and so attract. 

Ten: Energy Conservation 

Perhaps one of the simplest but still amazing concepts is that no matter what happens energy is always conserved, Energy in= Energy out. When using electronics or using your very own body you expend energy, but that energy doesn't just disappear it just takes on a different form. Ever touched a computer that's been on for a long time? Feels hot doesn't it, heat is just energy in it's simplest form (think of the sun). Other things such as the noise is also another form of energy. Energy in = energy out, it is always conserved. We can neither create nor destroy energy, just change it's form.