How Do Forces Change Motion? Exploring Newton’s Laws

Content Standards

In this lesson, learners demonstrate an understanding of force as a push or pull, the relationships among force, mass, and acceleration, the concept of inertia, action–reaction force pairs, and the role of net force in changing motion.

Performance Standards

Students will be able to:

Distinguish between balanced and unbalanced forces and predict motion outcomes.
Explain Newton’s Laws of Motion
Use F = m × a to relate force, mass, and acceleration (Second Law).
Identify action–reaction pairs in real-world situations (Third Law).
Interpret simple data from force–motion investigations.

Alignment Standards

Reference: NCERT Book Alignment

The lesson is aligned with the NCERT Grade 9 Science Book-Chapter 8: Forces and Laws of Motion, Section : 8.2, 8.4, 8.5 Newton’s Laws of Motion.

Learning Objectives

By the end of the lesson, students will be able to:

Define force, inertia, mass, acceleration, and action–reaction.
Identify examples of Newton’s First, Second, and Third Laws in daily life.
Use F = m × a in simple numerical problems involving carts or blocks.
Predict motion outcomes when forces are applied to objects of different masses.

Prerequisites (Prior Knowledge)

Basic idea of motion: rest vs moving objects.
Awareness that pushes and pulls can move things.
Understanding of the concept of energy and its importance for life.
Familiarity with measuring mass (grams / kilograms).

Introduction

In this session, students will discover that heavier objects are “harder to push,” moving objects keep rolling until friction stops them, and rockets move up while gases go down. This lesson channels those observations into a structured exploration of Newton’s Laws—building from curiosity to explanation through hands-on and virtual investigations.

Timeline (40 Minutes)

Title	Approximate Duration	Procedure	Reference Material
Engage	5	Video clip: skateboarder jumping off board → “Why does the board roll backward?” “Why does your body lurch in a bus when it stops?” Spark: Does motion need force to keep going?	Slides
Explore	10	Station rotation: Push light vs heavy carts; Try starting/stopping both. Record: Which was easier to start? Stop? Students predict “ rules” of motion from observations.	Slides
Explain	10	Teacher connects observations to Newton’s 3 laws; Introduce terms; inertia,net force, F = m x a, action -reaction pairs. Use diagrams + Virtual Lab: apply forces, vary mass, see accelerations; collision demo for action -reaction.	Slides + Virtual Lab
Evaluate	10	Students will attempt the Self Evaluation task on LMS.	Virtual Lab
Extend	5	Scenario Thinking: Scenario discussion: Car crash → why seat belts matter? Rocket launch → which forces act? Students relate Newton’s Laws to sports, vehicles, and safety. Exit ticket: “One real-life example for each law.”	Slides

How Do Forces Change Motion? Exploring Newton’s Laws

Introduction

In this session, learners will study about how objects at rest tend to stay at rest, and moving objects tend to keep moving—unless a force acts. But how much does motion change when we push harder? Why do we get pushed back when we push something? Sir Isaac Newton described three fundamental laws that explain almost all everyday motion—from rolling footballs to launching rockets.

Theory

What is a Force?

A force is a push or a pull that can change the state of motion of an object (start, stop, speed up, slow down, change direction) or deform it. When several forces act, it’s the net force that determines the motion change.

Newton’s First Law

An object at rest remains at rest, and an object in uniform motion continues in the same straight line unless acted upon by an unbalanced external force.

Inertia = resistance to change in motion.
Greater mass → greater inertia.
Examples: Passengers lurch forward when a bus stops suddenly; a coin on card remains when card is flicked.

Newton’s Second Law (Force–Mass–Acceleration Relationship)

The acceleration of an object is directly proportional to the net force applied and inversely proportional to its mass.
Mathematically: F = m × a (in SI: N = kg × m/s²).

More force → more acceleration (same mass).
More mass → less acceleration (same force).
Used to calculate motion changes in collisions, pushes, and propulsion systems.

Newton’s Third Law (Action–Reaction)

For every action, there is an equal and opposite reaction. Forces come in pairs acting on different objects.
Examples: A swimmer pushes water backward; water pushes swimmer forward. Rocket exhaust pushes gases downward; gases push rockets upward.

Momentum (Extension / Enrichment)

Momentum (p) = mass × velocity.
Changes in momentum relate to force and time of impact (impulse). Seat belts and airbags increase time of stopping → reduce force on passengers. (Use in extension activities if time permits.)

Why Are Newton’s Laws Important?

Explain motion in sports, vehicles, machines.
Support safety design (helmets, crumple zones).
Foundation for physics, engineering, and space science.

Vocabulary

This is the list of vocabulary terms used throughout the lesson.

Force – A push or pull that can change the state of motion or shape of an object.
Net Force – The vector sum of all forces acting on an object.
Inertia – The natural tendency of an object to resist any change in its state of rest or uniform motion.
Mass – A measure of the amount of matter in an object and a quantitative measure of inertia.
Acceleration – The rate of change of velocity with respect to time.
Newton (unit) – The SI unit of force; one newton is the force required to give a 1 kg mass an acceleration of 1 m/s².
Newton’s First Law – A body remains at rest or in uniform motion unless acted upon by an external unbalanced force.
Newton’s Second Law – The acceleration of an object is directly proportional to the net force and inversely proportional to its mass (F = ma).
Newton’s Third Law – For every action, there is an equal and opposite reaction.
Action–Reaction Pair – A pair of forces that are equal in magnitude, opposite in direction, and act on different bodies.
Momentum – The product of mass and velocity of an object, representing the quantity of motion.
Friction (supporting concept) – The resistive force that opposes relative motion between two surfaces in contact.
Balanced / Unbalanced Forces – Balanced forces produce no change in motion; unbalanced forces cause acceleration.

How Do Forces Change Motion? Exploring Newton’s Laws

Introduction

Welcome to the Newton’s Laws Virtual Lab!

Explore how forces change motion by experimenting with boxes, balls, and surfaces. See how objects move differently on friction and non-friction surfaces, how force affects acceleration, and how every action has an equal and opposite reaction. Test your understanding with fun challenges and quizzes as you explore all three laws of motion!

Key Features

Interactive Home Screen: Three clickable modules for the 3 laws of motion.
First Law (Inertia): Move a box on friction and non-friction surfaces to observe differences.
Second Law (Force & Acceleration): Adjust force slider to observe the object moving.
Third Law (Action–Reaction): Observe a ball hitting a wall with equal and opposite forces displayed.
MCQs and challenges integrated at the end of each module for engagement.

Step-by-Step Procedure for VR Experience

Step 1: Home screen displays 3 buttons – First Law, Second Law, Third Law. The user selects one to begin.
Step 2: In the First Law module, drag and push the box on a low-friction surface and observe motion.
Step 3: Switch to a high-friction surface and observe stopping behavior.
Step 4: Click Next to enter the Second Law module.
Step 5: Run simulation and view real-time calculation of acceleration (a = F/m).
Step 6: Click Next to enter the Third Law module.
Step 7: Launch a ball towards a wall and observe action-reaction force pairs.
Step 8: Complete the MCQ quiz for all three laws and view performance summary.