# Revision for Physics 2a

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What is the difference between speed and velocity?
Speed is how fast an object is moving, but velocity is how fat an object is moving in a certain direction
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What is the formula for acceleration?
Acceleration = change in velocity / time taken
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What does the gradient of a velocity-time graph represent?
Acceleration
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Explain the difference between weight and mass
Mass is the amount of matter in an object, but weight is caused by the pull of gravitational force
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What is meant by 'resultant force'?
It means a change in velocity
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If an object has a zero resultant force on it, what will happen to the object?
If the object is stationary, the object will remain stationary, but if the object is moving then it will carry on moving at the same velocity
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What is 'terminal velocity'?
The maximum speed of an object when all forces acting on the object are equal
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What are the two factors that affect the stopping distance of a vehicle?
Thinking distance and braking distance
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What is the formula for work done?
Work done = force x distance
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What's the formula for kinetic energy?
Kinetic energy = 1/2 x mass x speed^2
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Write down the equation that relates the force on a spring and its extension
F = k x e
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What is it called when the total momentum before and event is the same as after the event?
Conservation of Momentum
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Explain how air bags are useful in a crash
They slow you down more gradually and prevent you from hitting hard surfaces inside the car
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What is the advantage of using regenerative braking systems?
They store the energy of braking rather than wasting it
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What causes the build-up of static electricity?
It is caused by charges which are not free to move, so this causes them to build up in one place
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Which particles move when static builds up?
Electrons
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How does the resistance of a component affect the current?
The greater the resistance across a component, the smaller the current that flows
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How does the resistance of an LDR vary with light intensity?
The stronger the light intensity, the lower the resistance
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Give an application of an LDR
Automatic night lights
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## Other cards in this set

### Card 2

#### Front

What is the formula for acceleration?

#### Back

Acceleration = change in velocity / time taken

### Card 3

#### Front

What does the gradient of a velocity-time graph represent?

### Card 4

#### Front

Explain the difference between weight and mass

### Card 5

#### Front

What is meant by 'resultant force'?