Year 7 Science · Unit 3 · Lesson 7

Newton's Third Law — Action-Reaction Pairs

Foundation Worksheet

Name

Date

Class

Learning Goals

State Newton's Third Law: every action force has an equal and opposite reaction force.
Identify which object each force in a force pair acts on.
Explain why action-reaction pairs do not cancel each other out.

Warm Up

Sort it!

Write each force description from the pool into the correct column — "Action Force" or "Reaction Force." The first one is done for you as an example.

Rocket engine pushes exhaust gas downward Exhaust gas pushes rocket upward Swimmer's feet push off the starting block backward Starting block pushes swimmer forward into the pool Bird's wings push air downward Air pushes bird upward You push a wall with your hands Wall pushes your hands back toward you Earth's gravity pulls you downward (your weight) You pull Earth upward (tiny, but real)

Action Force (the first force applied)

Reaction Force (the equal and opposite response)

Your Turn

Match each action-reaction scenario to its force pair description

Draw a line connecting each scenario on the left to the correct force pair description on the right. Or write the matching letter next to each scenario.

Scenario	Your answer	Force pair description
A kookaburra flying through the air		A. Ball pushes back on bat with the same force; bat pushes ball forward
A cricket bat hitting a ball		B. Boat moves backward; jumper moves forward — forces on different objects
Jumping off a boat onto a jetty		C. Wings push air down; air pushes wings (and bird) up
A rocket launching into space		D. Foot pushes block back; block pushes foot forward into race
A swimmer leaving the starting block		E. Exhaust pushed downward; rocket pushed upward — equal and opposite
Standing still on the floor		F. Your weight pulls you down; floor pushes you up with equal normal force

Show What You Know

1. You push a skateboard ramp with 30 N of force. How much force does the ramp push back on you? On which object does each force act?

Recall 2 marks

2. A student says: "If action and reaction forces are equal and opposite, then everything should stay still — nothing would ever move." Explain why this student is wrong.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?