(Original post by inspiringsoul)
Is there any way I can help?
anyways here's a short check list of unit 4- (just skim through it)
Momentum = mass x velocity (vector quantity)
Units =Kgm/s or Ns
Momentum is always conserved in all types of collisions, explosions and interactions.
-The total momentum of a system before any interaction is equal to the total momentum after it PROVIDED no external forces act.
(as external forces would allow momentum to transfer to external bodies)
Change in 'p' =mv-mu
Rate of change of 'p' = (mv-mu)/t
(According to Newton's second law) , F is directly proportional to (mv-mu)/t
Hence F= ma AND Ft(impulse) = mv-mu
-Remember to use sign convention when you do momentum calculations
If u have solved the Jan 2011 paper, there was this 'newton cradle'-- and how to experimentally find the conservation of momentum, there are a lot of ways to do this- one being light gates, K.E.- P.E. formula, etc
Know the difference b/w elastic collision and elastic collision (In ELASTIC-K.E. is conserved, while INELASTIC- K.E. is not conserved)
- Know how to find the expression and learn how to derive it K.E =(p^2)/2m
-Know the basic formulae; v= r x omega ,T = (2pi)/omega , centripetal force F = (mv^2)/r , F = m x r x (omega)^2 etc
Remember - Centripetal force CANNOT do work on the particle, but it pulls the particle towards it centre.
Centripetal acceleration is at RIGHT angles to the velocity which is towards the centre of the circle, it DOES NOT cause an increase or decrease in speed of the body, only a change in direction.
btw, I prefer to understand how all the formulae are derived, as it's easier to remember, if there's any doubt, I could share with you.
Centripetal force is NOT produced by circular motion, it is the resultant force needed for circular motion, without it the object would travel in a straight line.
In hodder book, page 27 , there is a list of situations and 'what gives rise to centripetal force', so make sure.. u learn them. eg, vehicles taking a curve (which is the frictional force b/w the tyres and road) etc