Grade 9
  1. Mechanics  1.1. Motion  1.1.1. Types of motion  1.1.2. Distance and displacement  1.1.3. Speed and Velocity  1.1.4. Acceleration  1.1.5. Graphical representation of motion  1.1.6. Equations of motion  1.1.7. Uniform and non-uniform motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Relative speed  1.1.10. Circular motion  1.2. Laws of force and motion  1.2.1. The concept of force  1.2.2. newton's first law of motion  1.2.3. Newton's second law of motion  1.2.4. Newton's third law of motion  1.2.5. Inertia and types of inertia  1.2.6. Motion  1.2.7. Conservation of momentum  1.2.8. Application of Newton's laws in daily life  1.2.9. Types of Forces (Contact and Non-Contact)  1.2.10. Friction and its effects  1.3. Gravitational force  1.3.1. Newton's law of universal gravitation  1.3.2. Importance of Gravitational Force  1.3.3. Acceleration due to gravity  1.3.4. Free fall and weightlessness  1.3.5. Mass and weight  1.3.6. Variation of g with height and depth  1.3.7. Kepler's laws of planetary motion  1.3.8. Satellites and their orbits  1.4. Work, Energy and Power  1.4.1. Concept of work  1.4.2. Positive and negative actions  1.4.3. Work done by constant and variable force  1.4.4. Energy and its forms  1.4.5. Kinetic energy and potential energy  1.4.6. Law of conservation of energy  1.4.8. Commercial unit of energy  1.4.9. Work–energy theorem  1.5. Simple machines  1.5.1. Types of simple machines  1.5.2. Mechanical advantage  1.5.3. Machine efficiency  1.5.4. Levers and their types  1.5.5. Pulleys and Inclined Planes  1.5.6. Gears and their uses
  2. Properties of matter  2.1. States of matter  2.1.1. Solids, liquids and gases  2.1.2. Properties of different states of matter  2.1.3. Change in state of matter  2.1.4. Plasma and Bose–Einstein condensate  2.2. Density and pressure  2.2.1. Concept of density and relative density  2.2.2. Pressure in solids, liquids and gases  2.2.3. Pascal's law and its applications  2.2.4. Atmospheric pressure and its variations  2.2.5. Surface tension and capillarity  2.3. Buoyancy and Archimedes' principle  2.3.1. Buoyant force  2.3.2. Archimedes principle  2.3.3. Applications of Archimedes' Principle  2.3.4. floating and sinking objects  2.3.5. Theory of Flotation and Archimedes' Principle
  3. Heat and Thermodynamics  3.1. Temperature and heat  3.1.1. Concept of heat and temperature  3.1.2. Temperature measurement  3.1.3. Temperature scales  3.2. Heat transfer  3.2.1. Conduction of heat  3.2.2. Convection of heat  3.2.3. heat radiation  3.2.4. Applications of heat transfer  3.2.5. Thermal conductivity  3.3. Thermal expansion  3.3.1. Expansion of solids, liquids and gases  3.3.2. Abnormal expansion of water  3.3.3. Applications of Thermal Expansion  3.4. Specific heat capacity and latent heat  3.4.1. Concept of specific heat capacity  3.4.2. Measurement and applications of specific heat  3.4.3. Latent heat of fusion and vaporization  3.4.4. Heat Engines and Efficiency
  4. Waves and sound  4.1. Waves and their types  4.1.1. Mechanical and electromagnetic waves  4.1.2. Longitudinal and Transverse Waves  4.1.3. Properties of Waves  4.1.4. Wavelength, frequency and speed of the wave  4.1.5. Superimposition of waves  4.2. Sound waves  4.2.1. Nature and transmission of sound  4.2.2. Speed of sound in different mediums  4.2.3. Reflection of sound and echo  4.2.4. Sonar and ultrasound  4.2.5. Resonance and pulsation  4.3. Sound characteristics  4.3.1. Intensity, loudness and quality of sound  4.3.2. Doppler effect in sound
  5. Lighting and Optics  5.1. Reflection of light  5.1.1. Laws of reflection  5.1.2. Reflection from a plane mirror  5.1.3. Reflection from a spherical mirror  5.1.4. Image formation by concave and convex mirrors  5.1.5. Applications of Reflection  5.2. Refraction of light  5.2.1. Laws of refraction  5.2.2. Refractive index  5.2.3. Refraction through a glass slab  5.2.4. Refraction in water and air  5.2.5. Lenses and their types  5.2.6. Image formation by convex and concave lenses  5.2.7. Total internal reflection and its applications  5.3. Dispersion and scattering of light  5.3.1. Spectrum of white light  5.3.2. Prisms and Dispersion  5.3.3. Tyndall effect and blue sky
  6. Electricity and Magnetism  6.1. Electric charge and static electricity  6.1.1. The concept of electric charge  6.1.2. Charging by friction, contact and induction  6.1.3. Electroscope and its working  6.2. Current Electricity  6.2.1. The concept of electric current  6.2.2. Ohm's Law and Resistance  6.2.3. Factors affecting resistance  6.2.4. Series and Parallel Circuits  6.2.5. Heating effect of electric current  6.2.6. Electric power and energy  6.3. Magnetism  6.3.1. Natural and artificial magnets  6.3.2. Properties of magnets  6.3.3. Earth's magnetism  6.3.4. Magnetic field and field lines  6.3.5. Electromagnets and their applications
  7. Modern Physics  7.1. structure of the atom  7.1.1. Atomic Structure and Subatomic Particles  7.1.2. Electrons, Protons, and Neutrons  7.1.3. Rutherford and Bohr model  7.2. Radioactivity  7.2.1. Types of radioactive emissions  7.2.2. Half-life and radioactive decay  7.2.3. Uses and Hazards of Radioactivity
  8. Space science and astronomy  8.1. The universe and its components  8.1.1. Stars and galaxies  8.1.2. Planets and Solar System  8.2. Satellites  8.2.1. Natural and artificial satellites  8.2.2. Use of satellites

Grade 9 → Mechanics ↓


Simple machines


In the fascinating world of physics, simple machines are basic mechanical devices that change the direction or magnitude of a force. They are the building blocks for more complex machinery. Simple machines make it easier for us to do work by allowing us to push or pull greater distances.

What are simple machines?

Simple machines are the most basic mechanisms that use mechanical advantage (also called leverage) to multiply force. They provide the basis for machines by offering basic force manipulation. The six classic simple machines are:

  • lever
  • wheel and axle
  • pulley
  • inclined plane
  • nail
  • screw

Lever

A lever is a rigid bar that rotates around a fixed point called a fulcrum. It is used to transfer force and increase power. Levers are divided into three categories based on the position of the fulcrum, the load and the effort:

  1. First class lever: In a first class lever, the fulcrum is located between the input force (effort) and the output force (load). Common examples include seesaws, scissors, and pliers. 
    Effort - Fulcrum - Load
    Base Effort Burden
  2. Second-class lever: In this type of lever, the load is placed between the fulcrum and the effort. Examples include the wheelbarrow, nutcracker, and bottle opener. 
    Fulcrum - Load - Effort
    Base Burden Effort
  3. Third-class lever: For a third-class lever, the effort is applied between the fulcrum and the load. This is common in tools such as pliers, hammers, and fishing rods. 
    Fulcrum - Effort - Load
    Base Effort Burden

Wheel and axle

The wheel and axle is a simple machine consisting of a large wheel attached to a smaller wheel or shaft called an axle. When the wheel is turned, the axle rotates with it, and vice versa. This can significantly reduce the amount of force needed to move an object.

Mechanical Advantage = Radius of Wheel / Radius of Axle
Axle wheel

Pulley

A pulley consists of a wheel on an axle designed to support and change the direction of motion of a taut cable or belt. Pulleys are used to lift heavy loads with little effort and are often combined to increase mechanical advantage.

  • Fixed pulley: It does not move and is used to change the direction of force.
  • Moving pulley: moves with the load and reduces the amount of input force required.
Mechanical Advantage = Number of Ropes Supporting the Load
Pulley

Inclined plane

An inclined plane is a flat supporting surface inclined at an angle, with one end higher than the other, used to raise or lower a load with less effort. It effectively reduces the force required to lift an object by spreading the work over a longer distance.

Mechanical Advantage = Length of Slope / Height
plane

Nail

A wedge is a tool that is thick at one end and thin at the other. It is used to split or cut objects and it produces force perpendicular to its edges (faces).

Nail

Screw

In physics, a screw is a bent inclined plane. It is characterized by a helical structure that converts rotational force into linear motion and force.

Mechanical Advantage = Circumference / Pitch
screw

Uses of simple machines in everyday life

Simple machines are all around us, helping to make our lives easier in countless ways. Here are some everyday examples:

  • Seesaws in playgrounds work like levers, allowing two people to easily lift each other up and down.
  • Wheelbarrows are excellent examples of wheel and axle systems that help move heavy loads with ease.
  • In flagpoles, fixed pulleys are used to raise and lower the flag, which does not require much force.
  • Ramps make it easier to move heavy objects to greater heights because they increase the distance over which the force can be applied.
  • Axes are simple wedges that help cut wood by applying force on one side and bending it outwards.
  • The screws used in the lid of the jar convert the rotational force coming from our hands into a stronger linear force, which closes the jar tightly.

Importance of simple machines

Even though these machines are called "simple," their significance is much deeper. Simple machines have existed since ancient times and were the precursors of modern technological advancements. Understanding them helps us understand the principles of work and energy, which are essential concepts in physics.

By using simple machines, humans have been able to apply their strength more efficiently, making it possible to build impressive structures and devices. By giving us the power to move, lift and operate machinery with little force, simple machines continue to play an important role in technology, engineering and everyday life.

We encourage enthusiasm to explore and learn about simple machines, as these concepts lay the foundation for understanding more complex mechanical devices.


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Simple machines

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