Year 8 - Science
Changing speed
Moving by force
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores speed, forces, and motion, including effects on objects. It covers deriving equations, calculations, and distance-time graphs. Learn to use force arrows, identify balanced and unbalanced forces, and understand their impact on movement.
Lesson Summary
You will learn to describe how the speed of an object changes throughout the time that a resultant force is acting on it.
Key Notes
- A resultant force can change the speed of an object.
- The speed of an object changes throughout the time a resultant force is acting on it.
- The greater the gradient (steeper the line) on a distance-time graph, the faster the movement.
Vocabulary To Learn
- resultant force: The overall effect of a set of forces acting on an object.
- speed: A measurement of how fast something is moving, found from the distance travelled divided by the time taken.
- dynamics trolley: A small wheeled cart used in motion experiments.
- acceleration: A change in speed or direction of movement.
Common Mistakes To Avoid
- Pupils can think that change in speed is instantaneous due to forces, not over a period of time.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
A resultant force can change the speed of an object. The speed of an object changes throughout the time a resultant force is acting on it.
2. Define this scientific word and use it in context. 'resultant force'
The overall effect of a set of forces acting on an object. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils can think that change in speed is instantaneous due to forces, not over a period of time. Correction: Demonstrate that objects continue to accelerate while the force is acting. Make the force easy to understand (e.g. a pulling string).
More Lessons In This Unit
- Calculating speed Study Guide
- Changing the speed of a parachute Study Guide
- Comparing the speeds of different parachutes Study Guide
- Interpreting distance-time graphs Study Guide
- Measuring speed accurately Study Guide
- Measuring speed: practical Study Guide
- Newton's First Law Study Guide
- Reading distance-time graphs Study Guide
- Streamlining Study Guide
Browse all guides in the Year 8 Science guide library.