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Definition of Work And Energy - SS1 Physics Lesson Note

Definition of Work:

In physics, work is defined as the transfer of energy that occurs when a force is applied to an object, and the object is displaced in the direction of the force. Work is a scalar quantity and is measured in joules (J). The mathematical formula for calculating work is:

Work (W) = Force (F) Displacement (distance)

Where:

- W is the work done on the object,

- F is the magnitude of the force applied,

- d is the magnitude of the displacement of the object.

Work can be positive, negative, or zero, depending on the relationship between the force applied and the displacement. Positive work is done when the force and displacement are in the same direction, negative work is done when the force and displacement are in opposite directions, and zero work is done when there is no displacement or no force applied.

Definition of Energy:

Energy is a fundamental concept in physics that refers to the ability of an object or system to do work. It is a scalar quantity and is measured in joules (J). Energy exists in different forms and can be converted from one form to another. The various forms of energy include:

1. Kinetic Energy: The energy possessed by an object due to its motion. The kinetic energy (KE) of an object is given by the equation:

  KE = (1/2)mv^2

   Where m is the mass of the object and v is its velocity.

2. Potential Energy: The energy associated with the position or condition of an object. There are different types of potential energy, including:

  • Gravitational Potential Energy: The energy possessed by an object due to its position in a gravitational field. It is given by the equation:

     PEg = mgh

     Where m is the mass of the object, g is the acceleration due to gravity, and h is the height or vertical position of the object.

  • Elastic Potential Energy: The energy stored in a stretched or compressed elastic object, such as a spring. It is given by the equation:

PEs = (1/2)kx^2     

Where k is the spring constant and x is the displacement of the spring from its equilibrium position.

3. Thermal Energy: The energy associated with the internal motion of particles within a substance. It is related to the temperature of the substance and is a form of kinetic energy.

4. Chemical Energy: The energy stored in the bonds between atoms and molecules within a substance. It is released or absorbed during chemical reactions.

The law of conservation of energy states that energy cannot be created or destroyed but can only be converted from one form to another. This principle is fundamental to understanding the behaviour of energy in various systems and processes.

In summary, work is the transfer of energy that occurs when a force is applied and an object is displaced, while energy is the capacity to do work and exists in various forms. The study of work and energy is crucial in understanding the behaviour of objects and systems and is applied in various fields of physics and engineering.

Recommended: Questions and Answers on Work, Energy, And Power for SS1 Physics
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