Science
Forces & Motion
Conceptual
11–12 yrs
Resultant Forces
合力
Description
Describe forces as vector quantities with both magnitude and direction, distinguish between balanced forces (zero resultant, no change in motion) and unbalanced forces (non-zero resultant, causes acceleration or deceleration)
Mastery Evidence
- Explains what a vector quantity is and why force is a vector
- Calculates the resultant force when two forces act in the same or opposite directions on an object
- Explains what happens to an object's motion when forces are balanced vs unbalanced
- Draws free body diagrams showing all forces on a stationary object (e.g. a book on a table)
Assessment Prompt
If your child was pushing a heavy box along the floor but it wasn't moving, could they explain all the forces acting on it and why it stays still even though you're pushing?
