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Measuring speed: practical
I can accurately measure the average speed of a trolley moving down a ramp.
Lesson 2 of 10
New
New
- Year 8
Measuring speed: practical
I can accurately measure the average speed of a trolley moving down a ramp.
Lesson details
Key learning points
- A ramp will produce a force that allows a dynamics trolley to roll down it.
- The average speed of the trolley can be found from distance and time measurements.
- Counting down ‘3, 2, 1, go’ helps start a stopwatch at the right moment.
- Observing with eyes in line with the finish line helps stop a stopwatch at the right moment.
Keywords
Dynamics trolley - A small wheeled object used to investigate movement.
Gradient - The steepness of a slope, the larger the gradient the steeper a slope is.
Timer - A device used to precisely measure time, usually to 0.1 s or 0.01 s.
Metre rule - A simple length measuring instrument.
Average speed - The overall distance travelled divided by the overall time for a journey.
Common misconception
Pupils may think that the constant force on the trolley will cause it to move at a constant speed.
Demonstrate that the trolly speeds up as it rolls, by finding speed near the start and near the end of the ramp.
Pupils are finding average speed in this lesson and timing accurately is important. Encourage pupils to do 'practice runs' to help them reduce their timing errors, and demonstrate how to position their heads to see the finish lines.
Teacher tip
Equipment
See additional materials.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Two balls roll the same distance; ball A takes 4 s and ball B takes 3 s. Which statements are correct?
Two balls roll the same distance; ball A takes 4 s and ball B takes 3 s. Which statements are correct?
Ball A was moving faster than ball B.
Ball A has a greater average speed than ball B.
Q2.Which of these are units for speed?
Which of these are units for speed?
m
N/s
s/m
Q3.Which pieces of information are needed to find the average speed of a toy car rolling across a desk?
Which pieces of information are needed to find the average speed of a toy car rolling across a desk?
The mass of the toy car.
The height of the desk.
The size of the forces on the car.
Q4.Five swimmers complete a 200 m race. Their finish times are shown. Starting with the fastest, put the racers in order of average speed.
Five swimmers complete a 200 m race. Their finish times are shown. Starting with the fastest, put the racers in order of average speed.
Q5.A bus is travelling at 2 m/s and moves for a time of 30 s. Which of these shows how to calculate the distance the bus has travelled?
A bus is travelling at 2 m/s and moves for a time of 30 s. Which of these shows how to calculate the distance the bus has travelled?
distance = 2 m/s + 30 s
distance = 2 m/s ÷ 30 s
distance = 30 s ÷ 2 m/s
distance = 30 s - 2 m/s
Q6.A skater in a race travels a distance of 800 m in a time of 125 s. Calculate their speed.
A skater in a race travels a distance of 800 m in a time of 125 s. Calculate their speed.
0.16 m/s
1.6 m/s
675 m/s
925 m/s
Assessment exit quiz
6 Questions
Q1.Match the key words to the explanations.
Match the key words to the explanations.
Q2.Which feature of a dynamics trolly allows it to roll without slowing down much?
Which feature of a dynamics trolly allows it to roll without slowing down much?
It is very light.
It is very heavy.
It produces its own driving force.
Q3.Which of these measures should be taken to accurately measure the time it takes for a dynamics trolley to roll between two points on a ramp?
Which of these measures should be taken to accurately measure the time it takes for a dynamics trolley to roll between two points on a ramp?
The ramp must have a high gradient (be steep).
Push the trolley at the start.
Look along the ramp from the start to the finish line.
Q4.A dynamics trolley is rolled a distance of 1.5 m, taking 3.0 s to cover the distance. What is the average speed of the trolley?
A dynamics trolley is rolled a distance of 1.5 m, taking 3.0 s to cover the distance. What is the average speed of the trolley?
2.0 m/s
3.5 m/s
2.5 m/s
4.5 m/s
Q5.A dynamics trolley is released on ramps with different gradients and is found to have a greater average speed on the steepest ramp. Which of these statements help explain the results?
A dynamics trolley is released on ramps with different gradients and is found to have a greater average speed on the steepest ramp. Which of these statements help explain the results?
The forces on the trolley are always balanced.
The greater the gradient, the smaller the resultant force acting on the trolley.
The frictional force keeps the trolley moving.
Q6.A student times a trolley rolling 1.00 m down a ramp three times. The times were 3.24 s, 3.44 s and 3.36 s. Calculate the average speed of the trolley.
A student times a trolley rolling 1.00 m down a ramp three times. The times were 3.24 s, 3.44 s and 3.36 s. Calculate the average speed of the trolley.
0.13 m/s
1.0 m/s
3.33 m/s
30.0 m/s
