Year 7 - Science
Balanced and unbalanced forces
Forces
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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 focuses on quantifying and comparing energy transfers in different processes, such as motion changes, electrical circuits, and fuel burning. It examines forces as interactions between objects, using diagrams and measurements, including contact and non-contact forces.
Lesson Summary
You will learn to use the idea of resultant force to explain whether a change of speed occurs or not.
Key Notes
- Two forces of equal size, acting in opposite directions on an object, are balanced.
- The resultant force is the sum of the forces acting on the object, taking into account their direction.
- When forces are balanced there is no resultant force and no change in speed.
- When there are two forces acting in opposite directions, the resultant force acts in the direction of the bigger force.
- The greater the resultant force on a given object, the greater or faster the change in speed.
Vocabulary To Learn
- balanced forces: Two forces of equal size acting in opposite directions on an object, are balanced. They fully cancel each other out so no change is caused.
- unbalanced forces: Unbalanced forces do not fully cancel out.
- resultant force: The 'force left over' is called the resultant force. Resultant forces cause changes in speed.
Common Mistakes To Avoid
- The direction of the (resultant) force shows the direction of motion.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Two forces of equal size, acting in opposite directions on an object, are balanced. The resultant force is the sum of the forces acting on the object, taking into account their direction.
2. Define this scientific word and use it in context. 'balanced forces'
Two forces of equal size acting in opposite directions on an object, are balanced. They fully cancel each other out so no change is caused. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: The direction of the (resultant) force shows the direction of motion. Correction: The direction of the resultant force shows the direction of the change (not the direction of motion). Forces make things change.
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