Work,energy and momentum.

Question	Answer
Units for momentum..	kgm/s
Momentum is CONSERVED whenever objects..	..interact.As long as no external forces are acting on them.
Energy transferred is the same as..	..work done.
Units for work done..	..Joules (J)
The law of the conservation of momentum is the idea that..	..whenever objects interact,the total momentum before the interaction is equal to the total momentum afterwards. (as long as no external forces act on them)
Side impact bars(in cars) and crumple zones 'give way' in an impact so increasing the...	...impact time.
Like velocity,momentum has both..	..size and direction.
We can use the conservation of momentum to find the..	..speed of a car before an impact.
In calculations,ONE DIRECTION must be defines as positive so momentum in the other direction must be..	..negative.
The gravitational potential energy of an object depends on..	..its weight and how far it moves vertically.
Firing a bullet is an example of an explosion.The bulet moves with a momentum in ONE DIRECTION and the gun 'recoils' with..	..equal momentum in the opposite direction.
When vehicles collide,the force of the impact depends on mass,	change of velocity and the duration of the impact.
When a force acts on an object that us able to move,or it is moving,its momentum..	..changes.
For a change in momentum,the longer the time taken for the change,	the smaller the force acts.
During a collision,the momentum of an object often becomes..	0, during the impact-the object comes to rest.
If the IMPACT TIME is short,	the forces on the object are large.As the impact time increases the forces become less.
Work done to overcome friction is mainly transferred into..	..energy by heating.
CRUMPLE ZONES in cars are designed to fold in a collision.This increases the impact time and so...	..reduces the force on the car and the people in it.
Seat belts and air bags spread the force across the chest and they also increase the..	..impact time.
Gravitational potential energy is energy stored in an object because..	..of its position in the Earths gravitational field.
If an object is moved vertically upwards it gains gravitational potential energy equal to..	..the work done on it by the lifting force.
Power is the rate of..	..transfer of energy.
All moving objects have..	..kinetic energy.
The greater the mass and the faster the speed of an object,	the more kinetic energy it has.
All moving objects have..	..momentum.

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Work,energy and momentum.

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	Created by HannahDarville over 11 years ago