New
New
Year 10
Edexcel
Foundation

Velocity on a graph (v=x/t)

I can sketch accurate displacement-time graphs of different motions.

New
New
Year 10
Edexcel
Foundation

Velocity on a graph (v=x/t)

I can sketch accurate displacement-time graphs of different motions.

Lesson details

Key learning points

  1. Velocity of an object is equal to the gradient of a displacement-time graph.
  2. A direction in which velocity and displacement are measured needs to be chosen.
  3. A negative gradient on a displacement-time graph (sloping downwards) represents velocity in the opposite direction.
  4. A negative value for displacement represents a position ‘behind’ the starting position.

Common misconception

Negative values on a displacement-time graph always represent motion that is backwards.

Provide opportunities for pupils to plot a range of displacement-time graphs in real time in order for them to understand how the graph represents different motions.

Keywords

  • Displacement - The displacement of an object is the distance and direction from a specific point. Displacement is a vector.

  • Displacement-time graph - A displacement-time graph shows the displacement of an object over a period of time.

  • Motion sensor - A motion sensor measures the distance between itself and an object. We can use the measurements to calculate and plot graphs of displacement, velocity and acceleration.

Allow pupils to plot displacement-time graphs in small groups using a motion sensor on their desk to detect the position of a dynamics trolley they move towards or away from the sensor. A piece of cardboard taped to the back of the trolley provides a reliable target.
Teacher tip

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

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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6 Questions

Q1.
Some swimmers compete in a 50m race. Their times are shown. Starting with the fastest, sort the swimmers in order of their speeds.
An image in a quiz
1 - 29.9 s
2 - 30.2 s
3 - 31.1 s
4 - 31.2 s
5 - 31.4 s
Q2.
Which of the following are vector quantities?
distance
Correct answer: displacement
speed
Correct answer: velocity
mass
Q3.
A rocket has a velocity of 200 m/s upwards. What distance will the rocket travel upwards in 30 s?
6.7 m
Correct answer: 6000 m
60 000 m
3000 m
600 m
Q4.
A jogger runs for 250 s and they end up 625 m west of their starting point. Calculate the average velocity of the jogger.
Correct answer: 2.5 m/s west
0.4 m/s west
375 m/s west
5.0 m/s west
Q5.
Two trains are travelling in the same direction. Train A has a speed of 6.5 m/s and train B has a speed of 5.5 m/s.
Correct Answer: 1.0 m/s, 1.0 metres per second, 1 m/s, 1 metres per second, 1.0 metres/second
Q6.
An small airplane travels 45 km north in 30 minutes. Calculate the velocity of the airplane in m/s.
An image in a quiz
1.5 m/s north
22 m/s north
Correct answer: 25 m/s north
1500 m/s north
6.6 m/s north

6 Questions

Q1.
Match the key word or phrase to the explanation.
Correct Answer:displacement,a vector which is the distance and direction from a point

a vector which is the distance and direction from a point

Correct Answer:velocity,a vector that gives speed and direction

a vector that gives speed and direction

Correct Answer:displacement–time graph,shows the displacement of an object over a period of time

shows the displacement of an object over a period of time

Correct Answer:motion sensor,measures the distance between an object and itself

measures the distance between an object and itself

Q2.
Which feature of a displacement-time graph shows the velocity?
the intercept on the displacement axis (y-axis)
the intercept on the displacement time (x-axis)
the area beneath the line
Correct answer: the gradient of the line
the maximum on the displacement axis
Q3.
An ultrasonic motion sensor is used to measure displacement of a ball. Put the stages in order to explain how the sensor works.
1 - the sensor sends out an ultrasound pulse
2 - the sound pulse travels to the ball
3 - the sound pulse reflects off the ball
4 - the sound pulse travels to the sensor
5 - the sensor detects the pulse
6 - the speed of sound and the time information use used to calculate displacement
Q4.
Which line on the graph show the highest velocity?
An image in a quiz
A (red)
B (blue)
Correct answer: C (black)
D (green)
Q5.
Select the options which describe the motion between 1 s and 5 s.
Correct answer: positive displacement
positive velocity
Correct answer: negative velocity
Correct answer: constant velocity
changing velocity
Q6.
A pupil has plotted a graph to show their movement as they run across the classroom. Why is this graph unrealistic?
An image in a quiz
Correct answer: The change in their velocity is too sudden.
Their velocity is too high for a human to run.
The velocity is too low for running.
It does not take into account the direction of travel.
They have not given the graph a title.