In Unit 4, we learned about momentum. This unit was one of the more useful units, because I felt as though it completely related to real life. The equation for momentum is p=mass x velocity. An object will have a large momentum if its mass or velocity is large, or if they both are. Here's a useful video to help get a better understanding of momentum. Of course you can't expect the momentum of an object to always remain constant. It is going to change, and this change in momentum is called impulse. There are a couple of vital equations when dealing with impulse. They are, impulse (J) = force x change in time, and J= change in momentum (p). To increase the impulse, you must either increase the force, time, or both. However, when the impulse is constant, force and time on he equation are inversely proportional. Meaning that when you increase one the other decreases. There is one law that applies to momentum and it is the law of conservation of momentum. It states that the only way to change the momentum of an object is to exert an external force on it. No net force or net impulse equals no change in momentum. The official way to say this is that in the absence of an external force, the momentum of a system remains unchanged. As far as impulse goes, one thing to note is that the impulse of a bouncing is greater, because not only must the object be brought to a stop, but it must also be thrown back again. Here's a helpful video to help you get a better understanding.
Next up is collisions, which are actually pretty interesting. As we already know momentum is conserved in collisions (The net momentum before= the net momentum after). There are two types of collisions, which are elastic (two objects bounce of one another) and inelastic (two objects stick together). We can figure out the momentum that colliding objects have by using the first equation in elastic collision and the second in inelastic collisions.
(Remember m=mass and v=velocity; also m1, ma, m2, mb, v1,v2,va, and vb are all before the collision.)
Lastly, we have complex collisions, which involve to objects in different directions crashing together.
They create a combined momentum in a combined direction in inelastic collisions. A pool ball is a good example of a complex elastic collision. The cue ball hits the 8 ball at an angle and they both travel in different directions. However, in complex collisions momentum is still conserved.
This unit provided some difficulties when it cam to the lab problem. I had a hard time figuring out how to manipulate the equation in order to get the slope. But, it taught me a very valuable problem solving skill. It showed me that in order for scientists to prove their data sometimes you must manipulate the equation y=mx+b. This unit relates to real life situations, because it can help you learn how to minimize injury in crashes by increasing the time with things such as pads or airbags, in order to lower the force
GO PHYSICS!
