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 ↓


Levers and their types


A lever is a simple machine that helps us lift heavy objects with less effort. It is one of the oldest tools known to humanity and has been used for thousands of years. This simple device works on the principle of balancing forces around a fixed point known as a fulcrum. In this guide, we will explore how levers work and what the different types of levers are.

What is a liver?

A lever is a rigid bar that rotates around a point . This point is called the fulcrum . With a lever, you apply a force at one end, known as the effort , to move an object at the other end, called the load . The beauty of levers lies in their ability to move heavy objects with a minimum of effort.

Formula for lever:
The basic formula relating to the lever is expressed as:

Effort × effort arm = weight × weight arm

Here:

  • Effort arm: the distance from the fulcrum to the point where the effort is applied
  • Load arm: the distance from the fulcrum to the point where the load is applied

Types of levers

Levers are divided into three different classes depending on the effort, load and position of the fulcrum. Let's take a closer look at each of them:

First class lever

In a first-class lever, the fulcrum is located between the effort and the load. This means that you apply the force at one end, and the load or object you want to move is located at the other end. An example of a first-class lever is a seesaw.

Example of a first class lever:

Effort Burden Base

A seesaw on a playground perfectly demonstrates this type of lever. When one child pushes down, the other child moves up.

Second class lever

In a second-class lever, the load is located between the fulcrum and the effort. This setup gives a mechanical advantage, meaning you can move heavier loads with less effort. A classic example of this lever type is a wheelbarrow.

Example of a second class lever:

Effort Burden Base

Imagine you are pushing a wheelbarrow full of soil. Your arms provide the effort to lift the handle, the wheel acts as the axle, and the soil is the weight.

Third class lever

In a third-class lever, the effort is placed between the fulcrum and the load. This setup does not usually provide a mechanical advantage, but it does increase the speed and distance at which the load can be moved. An example is a fishing rod.

Example of a third class lever:

Base Effort Burden

Think about casting a fishing line. The grip of your hand on the rod is the effort, while the base of the rod is the fulcrum, and the fishing hook is the weight.

Understanding mechanical advantage

The mechanical advantage of a lever tells us how easy it is to move a load using that lever. We calculate it as the ratio of the length of the effort arm and the length of the load arm. The formula is:

Mechanical advantage (MA) = Length of effort arm / Length of load arm

For a first-class lever, the mechanical advantage can be greater than, less than, or equal to 1, depending on the position of the fulcrum. In a second-class lever, it is always greater than 1. In a third-class lever, it is always less than 1.

Practical examples of levers

Levers are all around us and are used in countless tools and machines. Here are some more examples of each type of lever and how they are used in everyday life.

Examples of first class lever

  • Scissors: When you cut paper, the screw acts as the pivot, the handle is where you apply effort, and the blades act as the load.
  • Hammer claw: Used to pull nails out of surfaces. The fulcrum is at the entry point of the nail, the load is the nail itself, and the handle is the effort arm.

Examples of second class lever

  • Nail clippers: When you cut a nail, the cut piece exerts pressure on the base, your finger applies force, and the cutting edge becomes the weight.
  • Bottle opener: The point that opens the lid is called the fulcrum, while your hand applies force (the weight) to one end to remove the lid.

Examples of third class lever

  • Broom: When sweeping, the fulcrum of the broom is the end where it touches the ground, the effort is your hand, and the part touching the dirt is the weight.
  • Tweezers: These are used to pick up objects delicately. The effort applied in the middle, the fulcrum at one end and the load is what you lift.

Conclusion

Levers are important components of the mechanical world around us. These simple machines increase our ability to move heavy loads and perform tasks with efficiency and ease. By understanding the three classes of levers and their practical applications, we can better understand the role of physics in our daily lives.


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Levers and their types

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