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Science

Forces and Motion

Overview

Students investigate how balanced and unbalanced forces affect the motion of objects, connecting their observations to Newton's laws of motion.

Learning Objective
Students understand the relationship between forces and motion and can apply Newton's first and second laws to everyday situations.

Resources needed

  • A ball
  • A smooth flat surface
  • A ramp
  • Weights (stones) of different sizes

Lesson stages

0 / 7 done
  1. 1 Push a ball on a flat surface — it moves then slows. Ask: why does it slow? (Friction — an unbalanced force).
  2. 2 Ask: if there were no friction, would it stop? (No — Newton's first law: objects keep moving unless a force acts on them).
  3. 3 Introduce Newton's first law: an object at rest stays at rest; an object in motion stays in motion unless acted on by an unbalanced force.
  4. 4 Push the ball harder — it goes faster. Ask: what changed? (The size of the force).
  5. 5 Introduce Newton's second law: greater force = greater acceleration; greater mass = less acceleration for the same force.
  6. 6 Test: roll a small stone and a large stone down the same ramp — which accelerates more on the flat?
  7. 7 Ask: how do seatbelts use Newton's first law to protect passengers?

Tap a step to mark it as done.

Variations

  • Time balls of different masses rolling the same distance to compare acceleration.
  • Discuss how rockets work: force in one direction creates motion in the opposite direction (Newton's third law).
  • Measure the force needed to pull different weights across different surfaces.
More information

Teach: force, motion, accelerate, mass, balanced, unbalanced, inertia. Newton's first law can be restated simply: 'things keep doing what they are doing unless a force changes it.'

Focus on Newton's first law only — the idea of inertia — before introducing the second law.

Can students state Newton's first law in their own words? Can they give a real-life example of both a balanced and an unbalanced force situation?

A ball, a flat surface, and stones of different sizes are sufficient. No specialist equipment or force meters needed.

Students almost universally believe that a moving object needs a continuous force to keep moving. It is friction, not the absence of force, that stops objects.

Newton's laws of motion underpin all of classical mechanics and engineering. Understanding them is essential for secondary physics and for understanding everything from car safety to space travel.

Activity details
Primary Challenging 25 minutes 5 minutes prep Small Group, Whole Class Indoor & Outdoor
Topics
Forces Motion Newton's Laws