Physics Topic 4
- Created by: Claudia Frolish
- Created on: 12-12-12 10:09
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- Transport on the Track
- Momentum
- P = MV
- Units =kgms-1 Vector quantity
- Monentum of an object is a measure of the accelerating force, applied over a period of time, that is needed to bring an object from rest to the speed at which it is moving
- It could also be the force required over a period of time to bring the moving object to rest.
- Newton's Second Law
- F= MA
- Formula only holds true if mass remains contestant
- The rate of the change in momentum of a body is directly proportional to the resultant force applied to the body, and is in the same direction as the force
- F = ?p/?t
- The product of a force applied over a certain time is known as an impulse ?p = ?t x F
- Conservation of momentum
- Initial momentum = final momentum
- when no external forces act (in a closed system)
- Initial momentum = final momentum
- Explosions
- If a staintory object eplosed the total momentum of all its parts will be zero
- Because the initial momenum was zero!!
- If a staintory object eplosed the total momentum of all its parts will be zero
- Newtons third Law
- For every force there is an equal and opposite force
- In terms of momentum this means that for any forcing changing momentum in one direction must be encounter by an equal and opposite force to ensure over al momentum is conserved
- Collisions
- Elastic collison= kinetic energy is conserved
- Newtons cradle - a collision causedby non contact forces such as alpha particles being scattered by a nucleuses perfectly elastic
- Inelastic collisions are when keneticenergy si not conserved by transferred to other energy forms e.q. heat
- Ek = p2/2m
- 1 eV = 1.6 X10-19
- Elastic collison= kinetic energy is conserved
- Circular motion
- w = 2?f
- f-1/T
- Centripetal force = the force that causes acceleration towards the centre of the circle
- Fprce will be larger if the object has a large mass, the radius is small or is the velocity is large
- w = 2?f
- Momentum
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