The velocity of an object is its speed in a given direction.
The displacement of an object is the distance it travels in a particular direction.
Displacement and velocity are both vector quantities.
Velocity has a positive value in one direction and negative value in the opposite direction.

Common misconception

Pupils often have a tendency to believe that a velocity must have a positive value and have difficulty in associating a reverse in direction with a change in sign.

It is important to make sure pupils are secure in their knowledge of the vector–scalar distinction; use plenty of visual examples.

Keywords

Displacement - The displacement of an object is the distance travelled in a particular direction from a starting point.
Vector - A vector is a quantity with magnitude (size) and direction. Displacement and velocity are both vector quantities.
Velocity - The velocity of an object is its speed in a particular direction.

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.

A pupil measures the time taken for different sports balls to travel 30 cm. Use the times to put the balls in order of decreasing speed, starting with the fastest.

1 - ball D: 0.25 s

2 - ball A: 0.28 s

3 - ball B: 0.31 s

4 - ball C: 0.34 s

5 - ball E: 0.36 s

Q2.

Which three of these equations show the correct relationship between average speed, distance travelled and time taken?

Correct answer: average speed = distance travelled ÷ time taken

average speed = distance travelled × time taken

Correct answer: distance travelled = average speed × time taken

Correct answer: time taken = distance travelled ÷ average speed

time taken = distance travelled ÷ average speed

Q3.

What should be done with a single anomalous result in a set of five readings?

Change the value of the anomalous result to match the others in the set.

Correct answer: Repeat the test for the anomalous result and replace it with the new value.

Repeat the whole experiment from the start using different equipment.

Correct answer: Cross out the anomalous result and ignore it in any calculations.

Use the anomalous result in any calculations but not on the graph.

Q4.

A pupil measures the time it takes for a car to pass between two street lamps as 5.0 s. If the car is moving at 8.0 m/s, how far apart are the lamps?

3.0 m

13.0 m

1.6 m

0.6 m

Correct answer: 40 m

Q5.

Which of these is a correct definition of a scalar quantity?

A quantity with a very large value.

A quantity with a very small value.

Correct answer: A quantity that has a magnitude but not a direction.

A quantity that has a magnitude and a direction.

A quantity that always has a value of zero.

Q6.

A tennis ball was released from a height of 20 m and took 20 s to fall to the ground. Which statements about the speed of the ball are correct?

Correct answer: The average speed of the ball was 10 m/s.

The instantaneous speed of the ball was the same throughout the fall.

The highest instantaneous speed of the ball was 10 m/s

The highest instantaneous speed of the ball was less than 10 m/s

Correct answer: The highest instantaneous speed of the ball was greater than 10 m/s

Exit quiz

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6 Questions

Q1.

Match the key words or phrases to their definitions.

Correct Answer:displacement,the distance travelled in a straight line from a starting point

the distance travelled in a straight line from a starting point

Correct Answer:vector quantity,a quantity with a magnitude (size) and a direction

a quantity with a magnitude (size) and a direction

Correct Answer:scalar quantity,a quantity with a magnitude (size) but not a direction

a quantity with a magnitude (size) but not a direction

Correct Answer:velocity,the speed of an object in a particular direction

the speed of an object in a particular direction

Q2.

Which of these are examples of displacements?

Correct answer: 30 km north

Correct answer: 30 cm left

30 m

Correct answer: 30 m down

30 m/s

Q3.

A train takes 2 hours to travel from one station to another which is 150 km west of the starting point. Calculate the velocity of the train.

300 km/h west

150 km/h west

Correct answer: 75 km/h west

300 m/s west

75 m/s west

Q4.

A pupil walks 5 m north, 3 m south and then 2 m north. Which of these statements about the pupil's journey are correct?

The total distance travelled is 4 m.

Correct answer: The total distance travelled is 10 m.

Their final displacement is 10 m north.

Correct answer: Their final displacement is 4 m north.

Q5.

Two cars are approaching each other. Car A has a velocity of 4 m/s west and Car B has a velocity of 4 m/s east. What is the relative velocity (speed) of the two cars?

0 m/s

4 m/s

Correct answer: 8 m/s

16 m/s

Q6.

A pupil walks 10 m west in 10 s, 5 m east in 5 s and 15 m west in 25 s. Calculate the magnitude of the average velocity for the complete journey (do not give the direction).

Correct Answer: 0.5 m/s, 0.5 m/s west, 0.5 m/s w, 0.5 m/s W, 0.5 m/s left