New
New
Year 10
OCR
Foundation

# Displacement and velocity as vectors (v=s/t)

I can represent and calculate the velocity of moving objects.

New
New
Year 10
OCR
Foundation

# Displacement and velocity as vectors (v=s/t)

I can represent and calculate the velocity of moving objects.

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## Lesson details

### Key learning points

1. The velocity of an object is its speed in a given direction.
2. The displacement of an object is the distance it travels in a particular direction.
3. Displacement and velocity are both vector quantities.
4. 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).

## Starter quiz

### 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
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

### 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?
30 m
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
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