# Work energy and power class 9 pdf

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A lawn mower is pushed a horizontal distance of 20 m by a force of N directed at an angle of 30 o with the ground. What is the work of this force? A student lifts a 50 pound lb ball 4 feet ft in 5 seconds s.

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Some energy-forms are less useful to us than others for example if we see low-level heat energy. It is better to talk about the extraction or the consumption of energy resources for example oil, coal, or wind than the consumption of energy by itself. A bullet that is moving fast has a measurable amount of energy associated with it this is known as the kinetic energy. The energy is gained by the bullet because work was done on it by a charge of gunpowder which lost some potential chemical energy in this whole process.

Hot coffee has a measurable amount of thermal energy which it acquired through the work which is done by a microwave oven which in turn took electrical energy from the electrical grid. Whenever In practice work is done to move energy from one form to another there is always some loss of energy to other forms of energy such as heat and sound energies.

The standard unit which is used to measure work and energy done in Physics is the joule, which is denoted by the symbol J. You may have come across calories which is another unit of energy. In an item, the amount of energy of food is often written in Calories on the back of the packet. For example, a gram typical chocolate bar contains about Calories of energy. One Calorie is the amount of energy that is required to raise 1 kg of water by 1-degree celsius.

Wait now a question arises, why are we using kilograms here instead of grams? The answer to this lies that this is equal to joules per Calorie so that one chocolate bar contains 1. That's a lot of joules if we observe. One very frequent source of confusion that is created in people is that they have with the concept of work comes about when thinking about holding a heavy-weight stationary above our heads against gravity.

Through any distance, we are not moving the weight so no work is being done with respect to the weight. Yet, we are aware from our previous experience that we get tired when doing the same job. So what is going over here? What is actually happening here turns out to be that our bodies are doing work on our muscles to maintain the necessary tension which holds the weight up.

The body does this by sending a cascade of nerve impulses with respect to each muscle. Each impulse that occurs causes the muscle to momentarily release and contract. These things happen so fast that we might only notice a slight twist at first when we observe it. Though Eventually, the chemical energy is not enough available in the muscle and it can no longer keep us up. We then begin to shake and rest for a time being. So work is being done by us, but it is just not being done on the part of the weight.

Work is defined as the process of energy which is transferred to the motion of an object through the application of a force in physics which is often represented as the product of force and displacement. A force is said to do positive work when it is applied, the force has a component in the displacement direction of the application. Work which transfers energy from one place to another or from one form to another.

## Work and Energy-Notes

Some energy-forms are less useful to us than others for example if we see low-level heat energy. It is better to talk about the extraction or the consumption of energy resources for example oil, coal, or wind than the consumption of energy by itself. A bullet that is moving fast has a measurable amount of energy associated with it this is known as the kinetic energy. The energy is gained by the bullet because work was done on it by a charge of gunpowder which lost some potential chemical energy in this whole process. Hot coffee has a measurable amount of thermal energy which it acquired through the work which is done by a microwave oven which in turn took electrical energy from the electrical grid.

Closely related to work are energy and power. In this chapter we shall The energy for these processes comes from food. collects question papers, attends classes, •. Take a slinky as shown below. •. Ask a friend to hold one of its ends.

## Class 9 Science NCERT in Pdf Chapter 11 WORK AND ENERGY

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### Class 9 Science NCERT in Pdf Chapter 11 WORK AND ENERGY

This solution contains questions, answers, images, step by step explanations of the complete Chapter 11 titled Work, Power And Energy of Science taught in class 9. After you have studied lesson, you must be looking for answers of its questions. The displacement is, say 8 m, in the direction of the force. Let us take it that the force acts on the object through the displacement. What is the work done in this case? When do we say that work is done?

It is always recommended to start your preparation of the examination by making your foundation strong of the subject and then going ahead with the regular practice sessions. And then for practising, reference books of the subject plays an important role in giving to the students with an ample amount of questions for the study. To help students in answering the questions of the exam, we have come up with top-notch Evergreen Science Chapter 12 Work, Power and Energy Class 9. Our Solutions are equipped with a complete solving method of the questions of the Evergreen Science Chapter 12 Work, Power and Energy book and can also help you in your examination preparation. The Evergreen Science Chapter 12 Work, Power and Energy Class 9 have been drafted in an easy and understandable language for the students after taking into study the overall syllabus of the subject.

Class 9 Science NCERTin Pdf Chapter 11 WORK AND ENERGY download in pdf. Rate of Doing Work & Commercial Unit Of Energy POWER Rate at which.