Gravity

Mass

The mass of an object is a measure of the amount of matter it contains. The mass of an object is constant. It is the same on Earth, on the Moon and in space.

Amount of matter

An object's mass is a measure of the amount of matter that it contains.

Inertia

An object's mass is also a measure of how difficult it is to change the object's motion.
This is called inertia.
An object with a high mass has more inertia than an object with a lower mass.
It is difficult to move an object with a high mass (and high inertia), and once it is moving, the object’s motion is hard to stop.

Weight - Examples

Weight = mass x gravitational field strength.

Gymin'

This would be easier on the Moon, where the gravitational field of strength is lower.

Experiment

Both balls used are subject to the same gravitational field of strength.

Centre of Mass - Examples

Although the mass of an object is spread out across its body, it is possible to find a single point where all of the mass appears to be. This point is called the object’s centre of mass.

All in a single point

The centre of mass is the point through which an object’s weight appears to act.

Hanging objects

If an object is hung from a string, it will hang with its centre of mass directly below the point that it is hung from.

Toppling over

An object will fall over if its centre of mass is outside its base.
An object will fall off a surface if its centre of mass isn’t over the surface.

1Energy

2Electricity

3Particle Model of Matter

3.1States of Matter

3.1.1Atomic Structure

3.1.2Atomic Structure 2

3.1.3Density

3.1.4Density - Calculations

3.1.5Changes of State

3.1.6Exam-Style Questions - Density

3.2Heat

3.2.1Internal Energy

3.2.2Heat Capacities

3.2.3Internal Energy - Calculations

3.2.4Latent Heat

3.2.5Latent Heat - Calculations

3.2.6Latent Heat Experiments

3.3Particle Motion in Gases

3.3.1Particle Motion in Gases

3.3.2Particle Motion in Gases 2

3.3.3End of Topic Test - Particle Model of Matter

3.3.4Grade 9 - Particle Model of Matter

3.3.5Exam-Style Questions - Specific Heat Capacity

4Atoms & Radiation

4.1Atoms

4.1.1Atomic Model

4.1.2Atomic Model 2

4.1.3Atoms & Ions

4.1.4Isotopes

4.1.5Exam-Style Questions - Atomic Structure

4.2Radiation

4.2.1Radioactive Decay

4.2.2Radioactive Decay 2

4.2.3Types of Radioactive Emission

4.2.4Fission & Fusion

4.2.5Radioactive Decay Equations

4.2.6Radio. decay equations - Calculations

4.2.7Half Lives & Ionising Radiation

4.2.8Half Life - Calculations

4.2.9Uses & Dangers of Radiation

4.2.10Uses & Dangers of Radiation 2

4.2.11End of Topic Test - Atoms & Radiation

4.2.12Grade 9 - Radiation

4.2.13Exam-Style Questions - Radioactive Decay

5Forces

5.1Basics of Motion

5.1.1Basics of Motion

5.1.2Basics of Motion 2

5.1.3Basics of Motion 3

5.1.4Distance- & Speed-Time Graphs

5.1.5Average Speed - Calculations

5.1.6Acceleration - Calculations

5.1.7Uniform Acceleration - Calculations

5.1.8Grade 9 - Motion

5.1.9Exam-Style Questions - Motion

5.2Forces

5.2.1Gravity

5.2.2Gravity - Calculations

5.2.3Resultant Forces

5.2.4Newton Second Law - Calculations

5.2.5Force Diagrams

5.2.6Free Body Diagrams - Calculations

5.2.7Stretching a Spring

5.2.8Hooke's Law

5.2.9Hooke's Law - Calculations

5.2.10Elastic Potential Energy

5.2.11Elastic Potential - Calculations

5.2.12Exam-Style Questions - Elastic Potential Energy

5.3Effects of Forces

5.3.1Acceleration

5.3.2Acceleration 2

5.3.3Momentum

5.3.4Change in Momentum - Calculations

5.3.5Momentum - Calculations

5.3.6Moments

5.3.7Moments - Calculations

5.3.8Circular Motion

5.3.9Levers & Gears

5.3.10Stopping Distance

5.3.11Decelerations

5.3.12Stopping Distance - Calculations

5.4Pressure

5.4.1Pressure

5.4.2Pressure - Calculations

5.4.3Liquid Pressure - Calculations

5.4.4Pressure Changes

5.4.5End of Topic Test - Forces

5.4.6Exam-Style Questions - Pressure

6Waves

6.1Wave Basics

6.1.1Basics & Formula

6.1.2Wave Speed - Calculations

6.1.3Describing Waves

6.1.4Wave Frequency - Calculations

6.1.5Transverse & Longitudinal Waves

6.1.6Required Practical - Ripple Tank

6.2Waves at a Boundary

6.2.1Waves at a Boundary

6.2.2Waves at a Boundary 2

6.3Sound Waves

6.3.1Sound Waves

6.3.2Sound Waves 2

6.3.3Uses of Sound Waves

6.3.4Sound Waves - Calculations

6.3.5End of Topic Test - Introduction to Waves

6.3.6Exam-Style Questions - Wave Speed

6.4Electromagnetic Waves

6.4.1Properties

6.4.2Gamma, X-Ray & UV Light

6.4.3Infrared, Microwave & Radio Waves

6.4.4Properties 2

6.4.5Visible Light

6.4.6Visible Light 2

6.4.7Grade 9 - Waves

6.5Lenses

6.5.1Lenses

6.5.2Lenses - Calculations

6.5.3Images & Ray Diagrams

6.6Heat & Radiation

6.6.1Infrared Radiation

6.6.2Temperature

6.6.3Greenhouse Effect

6.6.4End of Topic Test - EM Waves, Lenses & Heat

6.6.5Exam-Style Questions - EM Radiation

7Magnetism

7.1Magnetism Basics

7.1.1Magnetic Materials

7.1.2Magnetic Fields

7.2Electromagnetism

7.2.1Electromagnetism

7.2.2Electromagnetism 2

7.2.3Motor Effect

7.2.4Magnetic Flux - Calculations

7.2.5Motors

7.2.6Induced Potential

7.2.7Induced Potential 2

7.2.8Generator Effect

7.2.9Generator Effect 2

7.3Transformers

7.3.1Transformers

7.3.2Transformers 2

7.3.3Transformers 3

7.3.4Transformers - Calculations

7.3.5Transformers 2 - Calculations

7.3.6End of Topic Test - Magnetism

7.3.7Grade 9 - Transformers

7.3.8Exam-Style Questions - Magnetic Fields

8Astrophysics

8.1Astrophysics

8.1.1The Solar System

8.1.2The Solar System - Calculations

8.1.3Orbits

8.1.4Orbits HyperLearning

8.1.5Life Cycle of a Star

8.1.6The Universe

8.1.7End of Topic Test - Astrophysics

8.1.8Exam-Style Questions - Astrophysics

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