Speed-time graphs | Maths | Quizalize & Oak National Academy

Starter quiz

What do we plot on the $x$ -axis of a distance-time graph?

distance

displacement

speed

time ✓
The gradient of this line is ______.

'4' ✓
The gradient of this line is ______.

'30' ✓
The gradient of this line is ______.

'-6' ✓
This distance-time graph shows an object moving at constant speed. The object is travelling at ______ km/h.

'80' ✓
Which of these is equivalent to $\frac{a}{b}$ ?

$ab^{-1}$ ✓

$a^{-1}b$

$(ab)^{-1}$

Exit quiz

Deceleration is the rate at which the ______ of an object is decreasing.

'speed' ✓
Which of these could be units of acceleration?

m/s

ms $^{-1}$

ms $^{-2}$ ✓

$\frac{\text{m}^2}{\text{s}}$

$\frac{\text{m}}{\text{s}^2}$ ✓
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?

'15 m/s' ✓
The speed-time graph shows the first 20 seconds of an object's journey. What happened between 3 and 5 seconds?

The object stopped.

The object slowed down.

The object travelled at a constant speed. ✓

The object moved backwards.
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 $^2$ ?

'2' ✓
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 $^2$ ?

'3' ✓

Worksheet

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Lesson Details

Key learning points

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