# P3

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what is the formula for kinetic energy?
Kinetic energy= 1/2 mv squared (m=mass, v=velocity in m/s)
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when a car stops its kinetic energy changes into heat in the brakes, tyres and road, what is the formula that shows this?
Work done by brakes= loss in kinetic energy
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What is the formula for the change in kinetic energy?
braking force x braking distance= loss in kinetic energy
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What are the factors that affect fuel consumption of a car? (5 things)
1- The amount of energy required to increase its kinetic energy, 2- The amount of energy required for it do work against friction, 3- Its speed, 4- How it is driven, e.g excessive acceleration and deceleration, constant braking and speed changes
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What is the formula for momentum?
Momentum=mass x velocity in kgm/s
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What are two formula for force?
Force= change in momentum/time and force= mass x acceleration
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Force can be reduced by reducing the acceleration, how? (Two ways)
1-Increasing stopping or collision time, 2- increasing stopping or collision distance
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What safety features help to reduce acceleration? (5 features)
1-Crumple zones, 2- Seat belts, 3-Air bags, 4-Crash barriers, 5-Escape lanes
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What safety features do modern cars have that absorb energy when a vehicle stops suddenly? (4 things)
1-Brakes that get hot, 2- Crumple zones that change shape, 3-Seat belts that stretch a little, 4- Air bags that inflate and suqash
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What happens to crumple zones, air bags and seat belts on impact?
Crumple zones- absorb some of the car's energy by changing shape or crumpling, Air bags-absorb some of the person's kinetic energy by squashing up around them, Seat belts- stretch a little so some of a person's kinetic energy becomes elastic energy
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What do crumple zones, seat belts and air bags do? (4 things)
1- absorb energy, 2- change shape, 3- reduce injuries, 4-- reduce momentum to zero slowly, therefore reducing the force on the occupants
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What is a primary safety feature that helps to prevent a crash?
ABS brakes
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How do ABS brakes work?
Wheel speed sensors send information to a computer about the rotational speed of the wheels. The computer controls the pressure to the brakes, via a pump, to prevent the wheels locking up.
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What do ABS brakes do?
Increase the braking force just before the wheels start to skid
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## Other cards in this set

### Card 2

#### Front

when a car stops its kinetic energy changes into heat in the brakes, tyres and road, what is the formula that shows this?

#### Back

Work done by brakes= loss in kinetic energy

### Card 3

#### Front

What is the formula for the change in kinetic energy?

### Card 4

#### Front

What are the factors that affect fuel consumption of a car? (5 things)

### Card 5

#### Front

What is the formula for momentum?