# P2.1- Motion

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What does the gradient line on a distance–time graph represent?
Speed
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On a distance–time graph for a car, what happens to the line on the graph when the speed is increased?
The line gets steeper (its gradient is increased).
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How could we tell from the graph if the car was stationary?
The line would be horizontal.
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What is the scientific unit of speed?
metre per second, or m/s
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Write down the equation for calculating the speed of an object moving at constant speed.
Speed = distance / time
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Why are long-distance vehicles fitted with tachographs?
To check that their drivers don’t drive for too long
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How can you use a distance–time graph to calculate the speed a lorry was travelling at?
By dividing the distance travelled over the time taken
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What is velocity?
Velocity is speed in a given direction.
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Why does the velocity of a plane change as it ‘loops the loop’ at constant speed?
The direction of motion changes constantly, so its velocity also changes constantly.
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What is acceleration?
The change of velocity per second
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What is the scientific unit of acceleration?
metre per second squared (m/s²)
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Write down the equation used to calculate acceleration.
Acceleration = change in velocity / time taken
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In the alternative equation "a = (v-u)/t" , what do the letters ‘u’ and ‘v’ represent?
u is the initial velocity, and v is the final velocity.
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What is deceleration?
Deceleration is the change in velocity per second when an object slows down.
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Give another name for deceleration.
Negative acceleration
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When an object is accelerating, why does the line on its velocity–time graph go up?
Because its velocity is increasing with time
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How can we tell from a velocity–time graph whether the acceleration of an object was constant?
The line would be straight.
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What does the gradient of a line on a velocity–time graph represent?
Acceleration
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What would the line look like on a velocity–time graph for an object moving at constant speed?
It would be straight and horizontal.
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If the line goes down, what does this tell us about the motion of the object?
It’s slowing down, or decelerating.
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How do we find the distance travelled from a velocity–time graph?
By calculating the area under the line
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What does the gradient of a distance–time graph tell us?
The speed of the object
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Now use the graph to calculate the speed of the object.
Speed = gradient of the line = height of the triangle ÷ base of the triangle = 30 ÷ 10 = 3m/s
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What can we tell about the speed of an object if its distance–time graph is not a straight line?
The speed of the object is changing.
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On a velocity–time graph, what does the height of the line (or triangle) represent?
The change of velocity
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What does the base of the triangle represent?
What does the base of the triangle represent?
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Why does the gradient of a velocity–time graph represent acceleration?
Because acceleration = change of velocity/time taken, which is the same as finding the gradient of the graph
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How would you calculate the distance travelled from the graph?
By calculating the area under the line, which is the area of the triangle
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## Other cards in this set

### Card 2

#### Front

On a distance–time graph for a car, what happens to the line on the graph when the speed is increased?

#### Back

The line gets steeper (its gradient is increased).

### Card 3

#### Front

How could we tell from the graph if the car was stationary?

### Card 4

#### Front

What is the scientific unit of speed?

### Card 5

#### Front

Write down the equation for calculating the speed of an object moving at constant speed.