Balanced and unbalanced forces
I can use the idea of resultant force to explain whether a change of speed occurs or not.
Balanced and unbalanced forces
I can use the idea of resultant force to explain whether a change of speed occurs or not.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning 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.
- 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.
Keywords
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 misconception
The direction of the (resultant) force shows the direction of motion.
The direction of the resultant force shows the direction of the change (not the direction of motion). Forces make things change.
To help you plan your year 7 science lesson on: Balanced and unbalanced forces, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 7 science lesson on: Balanced and unbalanced forces, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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Explore more key stage 3 science lessons from the Forces unit, dive into the full secondary science curriculum, or learn more about lesson planning.
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Starter quiz
6 Questions
Exit quiz
6 Questions
