# P3: Forces for transport

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• Created by: Theex
• Created on: 30-04-14 15:39
On a distance-time graph what does the gradient show?
Speed, it is calculated by y / x
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On a distance-time graph what does a flat part show?
Stopped
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On a distance-time graph what does a negative gradient show?
Coming back towards starting point
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On a distance-time graph what does a curve show?
acceleration
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On a speed-time graph what does the gradient show?
acceleration
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On a speed-time graph what does a flat area show?
Constant speed
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On a speed-time graph what does a steeper gradient show?
greater acceleration
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On a speed-time graph what does a +ve gradient show?
+ acceleration
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On a speed-time graph what does a -ve gradient show?
- acceleration or deceleration
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How do you find distance travelled on a speed-time graph?
Calculate area under the line
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What is the difference between velocity and speed?
Velcocity has a direction as well as a number, while speed is just a number
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what are the two units of g (gravity)?
N/Kg m/s^2
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How does mass differ from weight?
Mass is the amount of 'stuff' in an object while weight is the consequence of gravity and is measured as a force
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What causes acceleration?
Unbalanced forces acting upon an object
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What are the three types of friction?
Static - between solid surfaces, sliding - between moving solid surfaces, resistance/drag - from fluids (liquids and gases)
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What is the resultant force on an object when it hits terminal velocity?
0
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What 3 things affect thinking distance when stopping?
Speed, tiredness and driving under the influence
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What 4 things affect braking distance when stopping?
Speed, weight of vehicle, braking force and grip - which includes stuff like road and tire quality and weather
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Why does speed influence total stopping distance so much?
Because it affects both braking and thinking distance, it is also ^2 when calculating Ek so when speed doubles braking distance quadrupples
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What do car safety features do to reduce damage to the driver and passengers?
It increases the time over which the collision occurs, which reduces force (F = ΔM / t) and deceleration (a = Δv / t). They also absorb Ek as they change shape - crumple zones.
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Define: when work is done
When a force makes an object move energy is transferred an work is done.
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What is GPE dependant upon?
The height the object is above the ground.
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Wha is the equation to show the stopping of a car?
F * d = 1/2 * m * v^2 or work done by brakes = Ek
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Define: power
A measure of how quickly work is done
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Is a high mpg value good or bad?
Good
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Is a high 1/100Km good or bad?
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What 5 things affect fuel consumption?
Size of engine, style of driving, mass of vehicle, speed and road conditions
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What are 3 issues of fossil fuels?
They lead to acid rain and contribute to the green house effect. They're also non-renewable.
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What are 3 advantages of biofuels?
Don't release many pollutants, they're renewable and have the potential to be carbon neutral
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What are 2 advantages of electric powered cars?
No pollution released when they're used and using solar panels reduce no pollution at all.
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What are 3 issues of electric powered cars?
Need to be charged, and creating that electricity causes pollution, solar panels are expensive and pollution is made during production. Also they're very limited in performance at the moment.
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## Other cards in this set

### Card 2

#### Front

On a distance-time graph what does a flat part show?

Stopped

### Card 3

#### Front

On a distance-time graph what does a negative gradient show?

### Card 4

#### Front

On a distance-time graph what does a curve show?

### Card 5

#### Front

On a speed-time graph what does the gradient show?