Momentum (T1) Flashcards
How do you calculate momentum?
Momentum (p) = mass (m) x velocity (v)
p = mv
Explain the law of conservation of momentum..
The total momentum of all objects before a collision is always equal to the total momentum of all the objects afterwards.
This is only true if there are no forces acting on the colliding objects except the forces they apply to one another.
Momentum is a …….. possessed by …….. in ………
Momentum is a quantity possessed by masses in motion
What is momentum a measure of?
Momentum is a measure of how difficult it is to stop something moving.
Whats is momentum measured in?
Kilogram metres per second
Kgm/s
The rate of change in momentum is directly proportional to….
….the force causing the change.
ie: if you double the force acting on an object its momentum will change twice as quickly
How do you calculate the increase in momentum of an object?
Increase in momentum = mv - mu
Initial momentum = mu
Final momentum = mv
Rearrange the following formula and explain what needs to be constant in order to make the rearrangement possible:
F = (mv - mu) / t
F = (mv - mu) / t
F = m(v - u) / t
(v - u) / t = a
F = ma
This rearrangement is only possible so long as the MASS of the object is constant
With regards to forces what does the terms ‘impulse’ refer to?
The term impulse refers to the product “force x time”
Momentum before a collision is equal to..
The momentum after a collision
Force x time = ?
Force x time = increase in momentum (impulse)
What is an elastic collision?
A collision in which no kinetic energy is lost.
What is an inelastic collision?
A collision in which two objects collide and stick.
How can the law of conservation of momentum be applied to explosions? Give an example..
The momentum before and after an explosion is the same, but there is a huge increase in kinetic energy.
Rockets use the law of conservation of momentum to propel space craft through space.
The produce a continuous, controlled explosion forcing large amounts of fast moving gases out the back of the rocket.
The space craft gains an equal amount of momentum in the opposite direction to that of the moving exhaust.
What are crumple zones in cars?
A safety feature used in modern cars.
They are zones or areas in front of and behind passenger compartments that crumple on impact and increase the time during which the car is decelerating.
