🧲 PhysicsGrade 7

Distance–Time Graphs

Objective: To describe motion from a distance-time graph and to find speed from the gradient of the line.

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What is steady speed?

A steady (uniform) speed means an object travels an equal distance in each equal interval of time. For example, a steady speed of 10 m/s means a car travels a distance of 10 m every second.

📖 Distance-Time Graphs — Slides 1, 7

Which axis is which?

In a distance-time graph, time is the independent variable and is plotted on the x-axis (horizontal axis). Distance is the dependent variable — it changes with time — and is plotted on the y-axis (vertical axis). Before plotting, you must choose and write a scale for each axis (for example, 1 cm = 1 second on the x-axis, 1 cm = 10 m on the y-axis), and label both axes clearly.

📖 Distance-Time Graphs — Slides 4–5

A horizontal line means stationary

The distance-time graph of an object that is not moving is a horizontal line parallel to the x-axis, because its distance from the reference point stays the same as time passes. For example, a car parked 50 m from a lamp post stays at 50 m at every time reading from 0 s to 5 s.

📖 Distance-Time Graphs — Slides 3, 6

Interactive Journey — feel the graph

drag the time slider below

Speed — first leg (m/s)0.5

Rest time (s)10.0

Speed — second leg (m/s)1.0

Time

0.0 s

Phase

🚶 Walking (first leg)

Speed now (gradient)

0.5 m/s

Live from the journey: at — s the object is at — m, loading… at — m/s.

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Practice Zone

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A worker cycles 200 m from home to the factory, taking 1 minute 40 seconds (100 s). Calculate the average speed. (Value + unit.)

✓ Graded instantly & deterministically — value, unit and direction checked by rules, not by an AI guess.

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