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4
80 ÷ 20 = 4 m/s.
Class 6 · English Version · General science
2026 Class 6 Science · English Version · Chapter 10 · Chapter companion part
Chapter 10: Motion
Distinguish distance from displacement and calculate motion using stated units.
Class 6 English Version chapter companion with expanded teaching, 20 written tasks and a notebook challenge. Further independent assessment and teacher-reviewed practical work remain; this is not complete textbook coverage.
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Learn the idea
An object is in motion if its position changes relative to a chosen reference. A seated passenger is at rest relative to a moving bus but moves relative to a roadside tree. Translational motion changes position; rotational motion turns about an axis; an oscillation repeats to and fro about a central position.
Distance and displacement
Distance is total path length. Displacement is the change from initial to final position and includes direction. A round trip can have positive distance but zero displacement. Keep a sign convention, such as east positive, when calculating along a straight line.
Speed and velocity
Average speed = total distance ÷ total time. Average velocity uses displacement ÷ time and includes direction. Uniform speed covers equal distances in equal times. For a turn, speed may stay constant while velocity changes because direction changes.
Acceleration and safe use
Average acceleration = change in velocity ÷ time; its unit can be m/s². A speed increase from 2 m/s to 8 m/s over 3 s gives 2 m/s² in a straight-line model. These calculations describe motion, not a reason to run near roads. Use supplied data or a paper model; follow road safety rules.
Recognise combinations of motion
A wheel can rotate about its axle while its centre translates along a road. The whole object can therefore show more than one kind of motion. Periodic motion repeats after equal time intervals; oscillatory motion moves to and fro about a central position. A repeated circular path is periodic without being a to-and-fro oscillation. Describe which part and reference object you mean.
Use a table and a stopwatch
For a safe motion observation, mark a distance, state the start and finish, and use elapsed time rather than a clock’s finishing reading alone. Reaction and reading errors can affect a short interval. Repeat a suitable observation or use supplied data. Equal distances in equal time intervals indicate uniform speed in the stated model; unequal distances need a more careful description.
Calculate across a whole journey
Average speed is total distance divided by total elapsed time. Include a stop if the question includes it in the journey. It is not generally the simple mean of listed speeds. Displacement uses start-to-finish position and direction instead of the whole path length. Acceleration uses change in velocity divided by time; choose a positive direction so a negative result has a clear meaning.
Connect the model to travel safety
For the same travel time, greater speed covers more distance; less time remains to respond to a hazard at a fixed distance. A classroom calculation does not determine a safe speed or legal limit for a real road. Use guardian/school travel guidance, seat belts where provided and safe designated crossing arrangements. Do not measure moving traffic or test braking on a road for this lesson.
Worked example
Walk 30 m east and 10 m west in 20 s. Distance = 40 m, displacement = 20 m east, average speed = 2 m/s and average velocity = 1 m/s east.
- Identify the evidence, quantity or structure in the question.
- Write a labelled method or explanation; include units where needed.
- Check the model, explain one correction, then attempt the independent task.
Check a common mistake
Average speed is not always the simple mean of two speeds: it uses total distance divided by total time. Distance and displacement answer different questions.
Average speed with unequal intervals
A supplied journey covers 12 m in 4 s, then 30 m in 6 s. Total distance = 42 m and total time = 10 s, so average speed = 4.2 m/s. Averaging the two segment speeds, 3 and 5 m/s, would give 4 m/s and answer a different calculation.
An acceleration sign
Take east as positive. Velocity changes from +10 m/s to +4 m/s over 3 s. Average acceleration = (4 − 10) ÷ 3 = −2 m/s², directed west in this straight-line model.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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17
Distance adds both path lengths: 12 + 5.
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7
12 − 5 = +7 m, or 7 m east.
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2
(11 − 3) ÷ 4 = 2 m/s².
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oscillation
An oscillation repeats about a central position.
Write in your own words. A guardian or teacher should review this response.
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The passenger is at rest relative to the bus seat but moving relative to a roadside object.
State two reference objects.
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Distance is the nonzero length of the lap; displacement is zero because the start and finish positions coincide.
Use both definitions.
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No. Velocity includes direction, which changes during the turn even if speed stays constant.
Distinguish a magnitude from direction.
Take it further
Apply the idea in a new situation and explain your method. Open writing needs a guardian or teacher to review it.
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4.2
(12 + 30) ÷ (4 + 6) = 4.2 m/s.
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2
Include the stop: 60 ÷ 30 = 2 m/s.
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12
20 − 8 = +12 m, meaning 12 m east.
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28
Distance counts the full path: 20 + 8 = 28 m.
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-2
(4 − 10) ÷ 3 = −2 m/s²; the acceleration is westward in the model.
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2
24 ÷ 12 = 2 s for one complete to-and-fro cycle.
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The wheel rotates around its axle while its centre translates relative to the road.
Name the part and reference used for each description.
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A uniform circular rotation repeats, but it does not move back and forth along a path about a central position as an oscillation does.
Distinguish repetition from to-and-fro motion.
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Average speed uses the total distance and the full elapsed time; omitting the stop changes the interval being described.
State the quantity measured and the interval.
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Human reaction in starting/stopping can affect the reading; time several repeated cycles or repeat a suitable controlled observation and describe the variation.
Use a safe practical model and do not hide differing readings.
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Time to reach the hazard is distance divided by speed; for the same distance a greater speed gives a shorter time.
Explain the relation without prescribing a real-road speed or conducting a road test.
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Rest and motion are described relative to a reference; the passenger is moving relative to the road or another chosen reference.
Name at least two references.
Your science notebook challenge
Create a motion notebook from supplied segment distances and times. Calculate total distance, displacement, average speed and one acceleration with a sign convention. Explain combined wheel motion and one school-approved travel-safety habit.
Review with a guardian or teacher
- Use an observation, labelled diagram or stated data.
- Explain how the evidence supports your answer.
- Record one limitation or correction with a guardian or teacher.
Keep your work on paper or in a local file. This page does not upload it or automatically grade the project.
Chapter companion and further study
This original Kidemy practice follows the topic order of 2026 Class 6 Science · English Version, chapter 10, printed pages 96–108. It does not replace the complete chapter or its practical teaching.
Official book catalogue and source →
Continue with your book or teacher
- Independent multi-stage motion problems and graph/table interpretation
- Teacher-reviewed safe timing observation and travel-safety communication
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