Collisions Flashcards
What is the principle of conservation of linear momentum?
The total linear momentum of a system remains constant in collisions provided no external forces are applied.
What happens with momentum in a closed system?
The total momentum before a collision = the total momentum after a collision.
What is the equation when pR_before is the momentum of the racket before and pB_after is the momentum of the ball after?
pR_before + pB_before = pR_after + pB_after
Is momentum a vector or a scalar?
Vector
What does momentum equal?
p=mv
What is key to remember about momentum?
It is a vector so it can include negatives providing different directions.
What are the 3 main types of collisions?
1) Elastic collisions
2) Inelastic collisions
3) Perfectly elastic collisions
In all the 3 main types of collisions what is the same?
Momentum is always conserved.
What is there no loss of in elastic collisions?
Kinetic energy is conserved
What happens with kinetic energy in an inelastic collision?
Kinetic energy is not conserved.
Give an example of an inelastic collision.
When two objects collide and stick together and then move off together.
Why are safety feature in a car?
They are put in place so they increase the collision time to minimise the force on the driver.
Name 4 safety features in a car.
1) Crumple zones- designed for the front of the car to fold in, in the event of a collision which increases the collision time.
2) Tyre Tread- designed for an increase in friction which help you brake in a shorter distance.
3) Air bag- The is designed to inflate really rapidly and to cushion you.
4) A seat belt- Designed to hold the occupants inside the vehicle so people don’t go shooting forward.
Define a perfectly elastic collision.
A collision where momentum is conserved, but kinetic energy is not conserved.
Define an inelastic collision.
A collision where momentum is conserved and the objects stick together after the collision.
