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Year 11
Higher

Speed-time graphs

I can calculate time intervals and acceleration of sections of a speed/time graph.

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New
New
Year 11
Higher

Speed-time graphs

I can calculate time intervals and acceleration of sections of a speed/time graph.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. In a speed-time graph, a horizontal line means the speed did not change during that time.
  2. A slanted line means the speed is changing.
  3. You find this by considering the change in speed with respect to the change in time.
  4. This is how you find the gradient of the line, which is also the acceleration.
  5. A negative gradient means there is deceleration.

Common misconception

Pupils may think a horizontal line on a speed-time means the object is stationary.

The $$y$$-axis is plotting speed so a horizontal line means the speed has not changed in that time. But this can be at any speed. Pupils need to double check axes to know what sort of graph they are using.

Keywords

  • Acceleration - Acceleration is the rate of change of speed with respect to time.

  • Deceleration - Deceleration is the rate at which the speed of an object is decreasing.

Using acceleration will be a new concept for most. You may wish to give pupils whiteboard or paper axes with a scale of 1:1 and get them to show and explore different acceleration rates before doing task B.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
What do we plot on the $$x$$-axis of a distance-time graph?
distance
displacement
speed
Correct answer: time
Q2.
The gradient of this line is .
An image in a quiz
Correct Answer: 4
Q3.
The gradient of this line is .
An image in a quiz
Correct Answer: 30
Q4.
The gradient of this line is .
An image in a quiz
Correct Answer: -6
Q5.
This distance-time graph shows an object moving at constant speed. The object is travelling at km/h.
An image in a quiz
Correct Answer: 80
Q6.
Which of these is equivalent to $$\frac{a}{b}$$?
Correct answer: $$ab^{-1}$$
$$a^{-1}b$$
$$(ab)^{-1}$$

Exit quiz

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6 Questions

Q1.
Deceleration is the rate at which the of an object is decreasing.
Correct Answer: speed
Q2.
Which of these could be units of acceleration?
m/s
ms$$^{-1}$$
Correct answer: ms$$^{-2}$$
$$\frac{\text{m}^2}{\text{s}}$$
Correct answer: $$\frac{\text{m}}{\text{s}^2}$$
Q3.
The speed-time graph shows the first 20 seconds of an object's journey. What was the top speed of the object in this time?
An image in a quiz
Correct Answer: 15 m/s, 15 metres per second
Q4.
The speed-time graph shows the first 20 seconds of an object's journey. What happened between 3 and 5 seconds?
An image in a quiz
The object stopped.
The object slowed down.
Correct answer: The object travelled at a constant speed.
The object moved backwards.
Q5.
The speed-time graph shows the first 20 seconds of an object's journey. Between 5 and 10 seconds the object was accelerating at a rate of m/s$$^2$$ ?
An image in a quiz
Correct Answer: 2
Q6.
The speed-time graph shows the first 20 seconds of an object's journey. Between 10 and 15 seconds the object was decelerating at a rate of m/s$$^2$$ ?
An image in a quiz
Correct Answer: 3