Field, contact and elastic forces

Repair the common break

Common misconception: A force must act in the direction of motion.

Correct model: Identify the interaction and direction independently of velocity; apply Hooke’s law only within its proportional range.

Worked transfer

A stretched spring pulling a trolley exerts an elastic contact force even if the trolley is momentarily moving toward the spring. Force direction comes from the interaction and deformation, not from velocity.

Guided practice

Explain why “A force must act in the direction of motion.” fails. Then construct one example that correctly applies field, contact and elastic forces.

Independent practice

Draw and label the forces on a falling magnet above a conducting plate, separating field and contact interactions and stating each direction.

Return to the recorded repair plan when the explanation and application are secure enough to re-test.