[Physics Class Notes] on Work and Energy Pdf for Exam

The word energy is used a lot in our day-to-day life. You have often heard people saying that they have exhausted their energy. Though it is used very commonly, it has a significant meaning. Energy is said to be the person’s ability to do or perform certain work. Energy can be stored as well as measured in numerous forms. 

Are you aware of the fact that energy can not be destroyed? Often people say that they have exhausted their energy but this energy can never be destroyed, it can just be transferred from one form to another form of energy. In this transformation of energy, work is done there. There are differences in energy, just like some forms of energy are more useful to us than other forms of energy. The two most common kinds of energies are kinetic energy and Thermal energy. For the time being, you can understand kinetic energy from the energy possessed by an obvious body such as that of a moving bullet. While we talk about Thermal energy it uses energy in the form of heat. A piping hot cup of your regular tea has his Thermal energy stored in it.

In practice, there is a fact that whenever work is done one form of energy is converted to another formidable energy and thus transfer of energy includes loss of energy at some points also. Let’s take an example of a traditional bulb: only 3% if the bulb is efficient for converting electrical energy to the visible light, while if we talk about a human being he is able to convert only 25% of its energy into chemical energy. Here, in this article you will get the knowledgefaber the energy and the work done. For Any work done energy is required and for doing work also energy is lost. In this article you will receive knowledge about what do this work and energy means, when we can say the work to be done,example if work done,energy, work energy principle, difference between work and energy and at last some recently asked questions that will help you to enhance your knowledge regarding this topic work and energy

What do Work and Energy State for?

In physics, the concept of work and energy is thoroughly correlated and linked to force. It is because whenever force is applied to any object, there is some work done and also some change in the energy. Work is a physical activity that includes movement in the direction of applied force. 

When is Work Done?

Work is said to be done when we apply a force which causes a movement in an object through a distance. According to physics definition, work defines itself only when an object is lifted or moved. However, it is not about an object in a stationary position. 

The amount of work done is equal to the product of the acceleration due to gravity, the actual mass of the object, and the height with which it has travelled. Generally, the work done against gravity is represented by the following equation:

W = m*g*h

Here, m= mass of an object

g= acceleration due to gravity

W= work done

h= height through which the object is raised 

The above diagram shows the two work sorts, namely; positive and negative. When the direction of the force applied is the same in which the object is displaced, then the work done is positive. When the applied force displaces the object in the opposite direction then the work done is said to be negative. 

Example of Work Done

When an individual kicks a ball, they are exerting an external force. Due to this external force, say F, the ball moves to some distance. The distance, with which a ball moves from its rest position to another position, refers to displacement, say d. Hence, work is said to be done, and its equation is given by:

Work = Force * Displacement

 or

W= F * d

The equation of the work states that work done is the product of applied force and displacement. If you are applying a force on the body and the movement is done then only you can tell the work to be done, otherwise, if there is no movement for your applied force then you have not done any work. Let’s take a simple example if you apply force on a wooden lock and the block moved then the work is said to be done by you but if you apply the same amount of force or even a bit of extra force for moving a wall the wall will not show any movement and thus the work is not said to be done in this case.

What is Energy?

Energy refers to the ability of an individual to do work. It can be either absorbed or destroyed and can transform from one object to another. The two general forms of energy are potential energy and kinetic energy. The most common way to measure energy is to measure the amount of work done or the ability of an individual to do work. Kinetic energy is the energy that is possessed by a body when in motion while potential energy is the energy possessed by the edify when it is in a rest state or still state.

The kinetic energy is given by the formula: K.E. = 1/2 * m * v2

P.E. = m * g * h

Different types of Energy are

The unit of the energy is given by Joule (J). It is the same as that of work.

Like work, energy also has magnitude but no direction. Thus,  energy is said to be a scalar quantity.

What is the Work-Energy Principle?

According to the principle of work and energy, the change in the kinetic energy of a body is directly proportional to or equivalent to the total work done on the body. The work-energy principle can be represented as:

Work was done = Final Kinetic Energy- Initial Kinetic Energy 

or

W = K_f – K_i

The work-energy principle is derivable from the physics law, that is, the conservation law of energy. 

The diagram shows a man applying force to move the box in the upward direction. In this case, the man’s kinetic energy is equivalent to the amount of work done in moving the box. 

What is the Difference Between Work and Energy?

• Whenever an applied force changes the object’s distance, it is said to be work done on an object. However, the ability to create or produce some work refers to energy.

• There is no further work; however, there are different types of energy, like sound energy, mechanical energy, and many more.
  

Work is said to be accomplished only if there is some displacement of the object. In case there is no displacement, but the force is applied, then the work done is zero. However, energy does not depend on whether some displacement is or not. For example, a man pushing a wall is applying force to move to a certain distance. The wall does not move, and hence the work done comes out to be zero. However, the energy of the man is released while pushing a wall.