3.4.1.6 Momentum Flashcards
What is momentum?
Momentum is the product of mass and velocity.
What is linear momentum?
Linear momentum is momentum in a straight line.
What is the equation for momentum?
Momentum = mass x velocity.
Is momentum a scalar or vector?
Momentum is a vector quantity, so has size and direction.
What is the unit for momentum?
Momentum = kgm/s.
What is the condition for momentum to be conserved?
Assuming no external forces act, momentum is always conserved. This means the total momentum of two objects before they collide equals the total momentum after the collision.
What are the 2 two types of collisions?
Elastic Collisions
Inelastic Collisions
What is an elastic collision?
An elastic collision is one where momentum is conserved and kinetic energy is conserved. No energy is dissipated as heat or sound.
The two objects bounce off each other.
What is an inelastic collision?
An inelastic collision is when some of the kinetic energy is converted into other forms during the collision. The momentum is still conserved.
The two objects join together and their mass combines.
What is Newtons Second Law?
Newtons 2nd law states that force is the rate of change of momentum.
The rate of change of momentum of an object is directly proportional to the resultant force which acts on the object.
What is the equation for the rate of change of momentum?
Force = Change in Momentum / Change in Time.
What is impulse?
Impulse is the change of momentum.
It is equal to force x time.
What is the unit for impulse?
Newton-seconds.
What does the area of a force - time graph?
Change in momentum.
How can the force of an impact be reduced?
By increasing the impact time.
What do crumple zones do?
Crumple zones are the parts at the front and back of the car that crumple up on impact.
This causes the car to take longer to stop, increasing the impact time and decreasing the force on the passengers.
What do seat belts do?
Seat belts will stretch slightly, increasing the time taken for the wearer to stop.
This reduces the forces acting on the chest.
What do air bags do?
These slow down passengers more gradually, and prevent them from hitting hard surfaces inside the car.
