Does anyone know a site where I can get detailed information about the concepts in Mechanics 2 Edexcel, coz I find the revision guide and the book itself not elaborate enough and a bit untidy.
work done = force x distance
work done = Kinetic Energy gained = 1/2mv^2-1/2mu^2
I was just wondering, is work done also:
work done = Kinetic Energy LOST = 1/2mu^2-1/2mv^2 ????
the book does not tell me if work done = kinetic energy lost, but I managed to do a question correctly in that book using that logic???!!!
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Edexcel M2 concepts watch
- 16-03-2004 21:06
- 16-03-2004 21:12
Yes, work done is energy gained by the object being moved in the direction of the force, therefore due to the law of conservation of energy, work done must be the energy lost by the object providing the force in the direction of the motion.
Think of the energy of one object the potential to do work to another. So if one object is travelling at a speed, or at a high temperature, it can potentially do work on another object (although in the temperature example you wouldn't use the equation W=Fx because the object having the work done on it isn't strictly moving, however the energy is still being transferred).
Hope this helps. Bottom line, work it the transfer of energy, so if object A loses 10J in an inelastic collision with object B, the work done is 10J on B, therefore not only does B gain 10J, but A (as stated) loses 10J.
- 16-03-2004 21:36
ahhh rite very well , that makes sense.
one more question, would u say overall KE lost = KE gained ?
- 16-03-2004 22:20
Yep, because of the conservation of energy. Except that sometimes doesn't hold, because kinetic energy can be transferred into other forms. If you throw a ball upwards, in flight the KE of the ball decreases but it isn't hitting anything and giving anything it's loss in KE. So we say it gains GPE, gravitational potential energy. If you hit a mallet on a wall, the KE of the mallet isn't making the wall move that much, most of the energy goes to sound energy.
It is important in Physics to remember the equation (when something with KE is slowing down due to gravity, or something is speeding up under gravity): KE = GPE
Use each formula, and with enough values you can equate them. It helps to have that in the back of your head in mechanics questions.
Sorry I seem to have gone off on a tangent. Anyway I guess I answered your question somewhere back in the 1st paragraph.