P2 - Momentum

Question 0

What is the unit of momentum?

Answer 0

Kg m/s

Question 1

What is the formula for momentum?

Answer 1

P = mv
Momentum = mass * velocity

Question 2

If a mass of 20kg was travelling at 10m/s, what would the momentum be?

Answer 2

200 kg m/s

Question 3

Is momentum a vector or a scalar?

Answer 3

Vector

Question 4

What is meant by “momentum is conserved”?

Answer 4

That momentum can’t be created or destroyed, it is only passed on

Question 5

If two objects of the same mass collided at the same velocity, the momentum would be 0kg m/s
Explain how this is possible

Answer 5

Momentum is a vector meaning there is a direction

In this case, the momentum is 0kg m/s because there is no resultant direction to the momentum

Question 6

How do we calculate change in momentum?

Answer 6

m(v - u)

Mass * (Final velocity - Initial velocity)

Question 7

How do you calculate the rate of change in momentum?

Answer 7

m(v - u) / t

(Mass * (final velocity - initial velocity)) / time

Question 8

How are force and momentum linked?

Answer 8

Force is the rate of change in momentum

Question 9

When an object hits another object and then stops, where is the momentum?

Answer 9

All of the momentum is in the other object that has been hit

Question 10

If an object hits another object and they both travel together, where is the momentum?

Answer 10

The momentum is in both objects

If the masses of the objects were the same, the final velocity would be half the initial velocity

Question 11

What is the equation that shows the conservation of momentum?

Answer 11

Resultant momentum before = resultant momentum after

Question 12

What are the 2 types of collision?

Answer 12

Elastic

Inelastic

Question 13

What happens to kinetic energy in elastic collision?

Answer 13

The kinetic energy is completely conserved

Question 14

What happens to momentum in an inelastic collision?

Answer 14

The kinetic energy is dispersed as other types of energy

Question 15

What is the formula for kinetic energy?

Answer 15

1/2 * mass * velocity^2

1/2mv^2

Question 16

How are force and momentum related?

Answer 16

Force is the rate of change of momentum

Question 17

Why are car crashes dangerous in terms of momentum and how are cars designed to take this into account?

Answer 17

In a car crash, momentum changes very quickly meaning that the forces in the body are very large (because force is rare of change of momentum)

Cars are designed to slow people down over a longer time when they crash so that the rate of change of momentum is smaller

Question 18

Describe the 4 ways that cars prevent injury in car crashes

Answer 18

Crumple zones at the front and back of the car crumple on impact which increases the impact time decreasing the force

Seat belts stretch slightly increasing the time taken for the wearer to stop

Side impact bars are strong metal tubes that direct the kinetic energy of the crash away from the passengers to areas of the car

Air bags slow you down more gradually and prevent you from hitting hard surfaces of the car

Question 19

How do regenerative braking systems work?

Answer 19

Rather than converting the kinetic energy to heat energy in brakes, it puts the motor in reverse

This slows the wheels and the motor acts as an electric generator to convert the kinetic energy into electrical energy which is stored as chemical energy in the battery