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Year 8

Measuring speed: practical

I can accurately measure the average speed of a trolley moving down a ramp.

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New
New
Year 8

Measuring speed: practical

I can accurately measure the average speed of a trolley moving down a ramp.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. A ramp will produce a force that allows a dynamics trolley to roll down it.
  2. The average speed of the trolley can be found from distance and time measurements.
  3. Counting down ‘3, 2, 1, go’ helps start a stopwatch at the right moment.
  4. Observing with eyes in line with the finish line helps stop a stopwatch at the right moment.

Common misconception

Students 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.

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.

Students are finding average speed in this lesson and timing accurately is important. Encourage students 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

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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Starter quiz

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6 Questions

Q1.
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.
Correct answer: Ball A was moving slower than ball B.
Ball A has a greater average speed than ball B.
Correct answer: Ball A has a lower average speed than ball B.
Q2.
Which of these are units for speed?
m
Correct answer: m/s
Correct answer: km/h
N/s
s/m
Q3.
Which pieces of information are needed to find the average speed of a toy car rolling across a desk?
An image in a quiz
The mass of the toy car.
Correct answer: The time it takes the toy car to travel.
The height of the desk.
Correct answer: The distance the toy travels.
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.
1 - swimmer E: 600 s
2 - swimmer C: 606 s
3 - swimmer D: 610 s
4 - swimmer B: 612 s
5 - swimmer A: 620 s
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?
An image in a quiz
distance = 2 m/s + 30 s
Correct answer: 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.
An image in a quiz
0.16 m/s
1.6 m/s
Correct answer: 6.4 m/s
675 m/s
925 m/s

Exit quiz

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6 Questions

Q1.
Match the key words to the explanations.
Correct Answer:dynamics trolley,A wheeled object used to investigate motion.

A wheeled object used to investigate motion.

Correct Answer:gradient,A measure of the steepness of a slope or ramp.

A measure of the steepness of a slope or ramp.

Correct Answer:timer,A device used to measure time.

A device used to measure time.

Correct Answer:metre rule,A device used to measure length.

A device used to measure length.

Correct Answer:average speed,Overall distance travelled divided by overall time taken.

Overall distance travelled divided by overall time taken.

Q2.
Which feature of a dynamics trolly allows it to roll without slowing down much?
An image in a quiz
Correct answer: The wheels have low friction.
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?
The ramp must have a high gradient (be steep).
Correct answer: Look directly across the finish line.
Push the trolley at the start.
Look along the ramp from the start to the finish line.
Correct answer: Start the trolley rolling with a countdown.
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?
Correct answer: 0.5 m/s
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?
Correct answer: The ramp is producing a force on the trolley which speeds it up as it rolls.
The forces on the trolley are always balanced.
The greater the gradient, the smaller the resultant force acting on the trolley.
Correct answer: The greater the gradient, the larger 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.
0.13 m/s
Correct answer: 0.30 m/s
1.0 m/s
3.33 m/s
30.0 m/s
Q2 UYSEG