2.3Unit 3: Forces, motion and pressure
Describing movement — Cambridge Checkpoint Physics 0893 Revision Notes & Topical Questions
5 min read 9 parts Lesson 3 of 7 1 quiz
Lesson summary
2.3 Describing movement — CHECKPOINT PHYSICS 0893 notes: Describe movement using distance-time graphs and calculate speed from them.Distance-time graph = a graph with distance on the vertical axis and time on the horizontal axisUse — it describes how an object movesAdvantages — t…
- Stationary
- On the graph
- Sketch graph
- Numbered axes
- Measurements
- Constant speed
Part 1 of 7Distance-time graphs
Distance-time graph
Distance-time graph a graph with distance on the vertical axis and time on the horizontal axis
Use
- Use it describes how an object moves
Advantages
- Advantages trends are easy to see, any value can be read, speed can be calculated and the whole journey is seen at once
Part 2 of 7What the sections show
| Line | Meaning |
|---|---|
| Straight upward slope | Constant speed away from the start |
| Steeper straight upward slope | Faster constant speed |
| Horizontal line | Stationary, distance does not change |
| Straight downward slope | Constant speed back towards the start |
Part 3 of 7Stationary objects
Stationary
Stationary not moving, with a speed of zero
At rest
- At rest another term for stationary
On the graph
- On the graph time passes but distance stays the same
Part 4 of 7A car journey
1Start
- Start at A the distance travelled is zero
2Section 1
- Section 1 constant speed from A to B
3Section 2
- Section 2 the car is stationary at B
4Section 3
- Section 3 constant faster speed from B to C
5Section 4
- Section 4 constant speed back to the start, A
Part 5 of 7Sketch graphs and graphs with numbers
Sketch graph
- Sketch graph a graph without numbers on the axes
Numbered axes
- Numbered axes values can be used for calculations
Speed
- Speed read distance from the vertical axis and time from the horizontal axis and use speed = distance ÷ time
Part 6 of 7Calculating speed from a graph
Read the distance covered in the section from the vertical axis.
Read the time taken in that section from the horizontal axis.
Divide the distance by the time.
Include the unit in the answer.
Example
- Example a train covers 2000 m in 200 s, which is 10 m/s, and returns 2000 m in 100 s, which is 20 m/s.
Part 7 of 7Investigating walking and running
Aim
- Aim find the average speeds for walking and running in m/s
Measurements
- Measurements measure a distance and time the person walking and running over it
Safety
- Safety the person running takes precautions, for example a clear flat area
Graph
- Graph draw walking and running on the same graph with lines labelled
Result
- Result the running line is steeper because more distance is covered in each second
Key terms
| Term | Meaning |
|---|---|
| Distance-time graph | Graph of distance against time showing movement. |
| Stationary | Not moving. |
| At rest | Stationary. |
| Sketch graph | Graph drawn without numbers on the axes. |
| Constant speed | Speed that does not change. |
| Average speed | Total distance divided by total time. |
Avoid these mistakes
1
Thinking a horizontal line means constant speed — it means stationary.
2
Thinking a downward line means slowing down — it means moving back towards the start.
3
Confusing a steeper line with a longer distance — it means a higher speed.
4
Reading values from the wrong axis — distance is vertical and time is horizontal.
Marked practiceQuizzes for this lesson
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