1. Work Done Kinetic Energy Momentum Vehicle Safety Features
Energy and Momentum
Work Done
Kinetic Energy
Momentum
Vehicle Safety Features

2. Work Work done is the transfer of energy
Work done (J) = Force (N) x distance (m)

3. Work done against gravity
Work done against gravity = Gravitational Potential Energy (GPE)
Flying saucer
Work done (J) = Force (N) x distance (m)
So Upwards:
GPE (J) = Weight (N) x height (m)
(weight = mass x gravity)

4. Work done against friction
Rub hands together
Brakes in a car

6. 40 mph
She has been hit initially on the pelvis. Her pelvis has broken. She has been thrown approximately 28m from the car, and has fallen to the ground onto her arm initially, with her head hitting the road next, causing her skull to be fractured (hence the trickle of blood from the ear, and the blood in the hair). She has grazes on the side of her face (on her cheeks and temple) from where she has slid along the road.

7. 30 mph
She has been hit initially on the pelvis. Her pelvis is bruised. Having been hit initially in the pelvis she is thrown approximately 16 metres and falls onto her side, fracturing her arm (though it would not look distorted). She then hits her head, but not so hard as to concuss her.

8. momentum (kg m/s)= mass(kg) x velocity(m/s)
Air track

9. Conservation of momentum
In some crashes momentum is conserved
Eg, snooker balls colliding
So total momentum before = total momentum after
Massb4 x velocityb4 = massafter x velocityafter

10. Vehicle safety features and momentum
Egg and sheet

11. force = change in momentum / time taken for the change
How crumple zones work
force = change in momentum / time taken for the change
Stays constant
Can change