# P2 Unit 4: Momentum, energy, work and power

• Created by: nicola
• Created on: 25-05-15 11:53
What is the stopping distance?
Stopping distance (m) = thinking distance (m) + braking distance (m). Stopping distance is the distance travelled from the time the driver sees a hazard to the time the car comes to a halt.
1 of 19
What is the thinking distance? 1/3
Thinking distance travelled from the time the driver sees a hazard to the time he applies the brake.
2 of 19
What is the thinking distnace? 2/3
The thinking distance is affected by the speed of the car and the driver's reaction time.
3 of 19
What is the thinking distance? 3/3
The driver's reaction time will increase if the driver is distracted (by a moblie phone or a cry child) or not in peak physical condititons e.g. old, tired, intoxicated (drugs and alcohol).
4 of 19
What is the breaking distance? 1/2
Braking distance is the distance travelled from the time the driver applies the brakes to the time the car come to a complete stop. The braking distance is affected by the speed of the car and the conditions of the car and road.
5 of 19
What is breaking distance? 2/2
A large (massive) car tralleving at high speed with poor brakes and worn tires on a slippery road surface (one with little friction between the tires and road) will have a long braking distance.
6 of 19
What is friction?
Friction is the force that resits motion. The greatert the friction the more force is reuired to get an object to move,
7 of 19
What is momentum and how does it work?
Monentum can be of as a measure of how different it is to stop something from moving. An object s momentum increase as its mass increase and its velocity increases. A fast moving fully loaded train has much more momentum than a slow moving Ping-Pong.
8 of 19
What else is momentum clased as?
Momentum is a vector it has a size and direction. (if two objects are travelling in opposite direction one will have a positive momentum and the other a negative momentum).
9 of 19
What happens to the momentum in a collions?
In a collision momentum is always conserved. Total momentum (of all the object) before the collision = the total moentum (of all the object) after the collision. (the momentum of one object is often transferred to another).
10 of 19
How do you change the momentum? 1/2
A force is required to change the momentum of an object. The quicker the momentum changes the larger forces required. e.g. to stop a fast moving heavy train in a short amount of time will require a large forces (from very good brakes).
11 of 19
How do you change the momentum? 2/2
In a car cash the momentum (velocity) of an object changes in a very short amount of time so the body feels a large which can damage it.
12 of 19
What car safety features are their? How do they help? 1/2
Airbag, crumple zones and seabelts all increase the time of collision. This means the mentum of the driver is changed over a longer time which reduces the force on the driver that could cause injures.
13 of 19
What car safety features are their? How do they help? 2/2
(Remeber sudden or short time collisons such as banging your head on a hard table hurt because there is a large reaction force. When bouncing on a trampoline the collision (between you and the trampoline takes longer time so the force is lower.
14 of 19
What is meant by the term work done?
Work done is a measure of how much energy has been transferred from one type of energy to another type of energy. E.g a light bulb that has transferred 5000J of electrical energy into the light and heat energy has to do 5000J of work.
15 of 19
What is meant by the term power?
Power is the amount of work done every second. How much energy is transferred per second. Power is measured in (W) Watts or J/s. E.g. a 50W light bulb transfer 50J of electrical energy every second into heat and light energy.
16 of 19
What is Gravitation Potential Energy?
The higher up an object, the more mass and the greater the gravitational field strength the more Gravitation Potential Energy it has. (Potential tells us the energy is stored up).
17 of 19
What is Kinetic Energy?
The faster and the more mass of an object has the more kinetic energy it has. The velocity of an object has more impact on the amount of energy the object has than it's mass.
18 of 19
What is the conserveation of Energy?
Energy cannot be created or destory only transferrred. Energy in = Energy out. If a light bulb is provided with 300J of electrical energy it will produce 300j of heat and light energy.
19 of 19

## Other cards in this set

### Card 2

#### Front

What is the thinking distance? 1/3

#### Back

Thinking distance travelled from the time the driver sees a hazard to the time he applies the brake.

### Card 3

#### Front

What is the thinking distnace? 2/3

### Card 4

#### Front

What is the thinking distance? 3/3

### Card 5

#### Front

What is the breaking distance? 1/2