A Moving All-Thing:Mass and Velocity
Momentum is the product of the mass of a body to its velocity. The change its momentum during impacts with other objects. There could be a change in mass during motion, rather than speed and this will cause a change in momentum also. Some example where mass could change are airflow, water coming out of a nozzle, sand being pour out of a bag etc.
For any reason, if the momentum changes, there has to be a force or a force has to cause it to happen. One way to write Newton's second Law is:
F = d(mv)/dt
You may need tutorials on solving algebra: Simple Algebra
and vectors: Vectors
You could write it this way:
Fdt= d(mv)
Acceleration relates to forces in a special linear relation: Acceleration
and on how acceleration works in a linear way: Simple Motion
A Short Time To Make It Happen In Golf: Impulse
A system consisting of several objects under-going collisions are said to conserve momentum if the change in momentum is always zero.
There are two extremes of collision: perfectly elastic and completely plastic.
Coefficient of impacts
The 'coefficient of restitution' reflects the capacity of the contacting bodies to recover from impact. It is given by the ratio:
e = (v22-v12)/(v1-v2)
=|velocity of separation|/|velocity of approach|
This means that for e to be 1, the difference in velocities after impact must be the same after impact as before impact. that is for the case of perfectly elastic collisions. If e were zero, there would not be a difference in velocities after impact and that would mean a plastic collision.
What Gives: Momentum Exchange
When there is a collision, the particles involved undergo changes in momentum. If we consider two bodies only, and say the first body with mass m1 moves with velocity v1 and the second with mass, m2 moves with v2, and say the bodies where moving in the same direction like below:
It is implied that v1>v2 because that is necessary for collision to occur. vc is the 'impact velocity'. Just imagine that you run towards your friend as you chase him and you meet him and give him a push. At that push the both of you are moving with the same velocity. But vc the reduces for m1 to v12and increases for m2 to v22.
The result is that in the end the total momentum before impact will be the same as that after impact:
m1v1+m2v2=m1v12+m2v22
This is for 'direct impacts' where the bodies collide as their centers are moving along paths that have tangents that superimpose and any perpendicular line on both tangents are parallel to each other. There are impacts that are not direct but happens at angles. These impacts need a different or a general kind of approach. The angles introduce velocities from or in two coordinates if you were dealing with plane motion and three coordinates if you were dealing with 3-D motion. We will show only plane motion here:
A Fall Is Covered: Potential Energy
Potential Energy is the set tendencies for an object to do work because how it is oriented if it was let through a threshold, like you would rather get hit by the side of a vehicle than its bonnet. You would probably still suffer a fling men, and some scraps and bruises and probably hit the ground hard but you also still probably survive. A thing that is heavy and placed well above your head better be sitting tight or else. A sharp knife is badder than a a rock pressed on you.
In physics books you most likely will deal with things falling through a distance at first. The formula for potential energy of a thing about to fall is:
P.E = mgh
m = mass of thing
g = acceleration due to gravity
h = height of fall
This energy can become useful when the object does fall or dangerous. In water falls it can be used to turn a turbine which can produce energy.
Oncoming and Crashes and Burns Into: Kinetic Energy
Kinetic Energy is the set tendencies for a moving object to do work against a resultant force set up resist it. You would rather be hit by a bicycle than a school bus moving at the same speed. The bus is heavier and will possess more force to fight with. But you would rather the bus than a bicycle moving at the speed of of a bullet. You would rather not the bullet at all. The formula for kinetic energy is:
K.E = (1/2)mv2
m = mass of thing
v = velocity at the time of consideration
One Into The Other: Energy Exchanges
Energy can be changed from one form into another. You can throw a ball onto the ceiling of your house which means you changed kinetic energy into potential energy. What actually is happening is changes. When the kinetic energy of an object changes, that change means something has gone somewhere or has come in from somewhere. Also for potential energy. If an orange drops from a tree and unto a car, it potential energy changes and just now became kinetic for a short while. There are also other forms energies could change into like stretch in springs like when kicking the brakes, or heat due to friction when the tyres hit or sound of the tyres... infact they usually happen all at once....
The way it is written is:
U = ΔP.E + ΔK.E +ΔOthers
U = Total energy of the isolated system
ΔP.E = changes in potential energy
ΔK.E = changes in kinetic energy
ΔOthers = changes in other forms of energy like stretches and losses like friction
For other studies in Physics go to: Physics
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