FBISE 9th class Physics Chapter 6 Work And Energy Short Questions with answers are combined for all 9th class(Matric/ssc) Level students. Here You can prepare all Physics Chapter 6 Work And Energy short question in unique way and also attempt quiz related to this chapter. Just Click on Short Question and below Answer automatically shown. After each question you can give like/dislike to tell other students how its useful for each.
Class/Subject: 9th Class Physics
Chapter Name: Work And Energy
Board: Federal Board
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FBISE 9th Class Physics Chapter 6 Work And Energy Short Questions Answers
Work is done when a force is acting on a
body displaces in the direction of a force. Work is a scalar quantity. It depends on the force acting on a body, displacement of the body, and the angle between them. Its SI unit is Joule (J).
A body possesses energy if it is capable to do work is known as energy.
The power of a body is one watt if it does work at the rate of joule per second (1Js-1).
The ratio of the useful work done by a device or machine to the total energy taken up by it is called its efficiency.
The energy possessed by a body due to its motion is called kinetic energy. e.g. Moving water in a river can carry wooden logs through large distances and can also be used to drive turbines for generating electricity.
The energy possessed by a body due to its position is known as its potential energy. e.g. stored water in the dam, A hammer is raised to some height can do work.
The energy present in a body due to its height is called gravitational potential energy. e.g. Stored water in the dam.
An ideal machine is that which gives an output equal to the total energy used by it. In other words, its efficiency is 100%. People have tried to design a working system that would be 100% efficient. But practically such a system does not exist.
The rate of doing work concerning time is called power. Its unit is the watt (W).
Work is said to be done when a force acts on a body and moves it in the direction of the force. Greater is the force acting on a body and longer is the distance moved by it, larger would be the work done. Mathematically, work is a product of force F and displacement S in the direction of the force. Thus
Work done = Force x displacement
W = FS
Energy is an important fundamental concept in science. It links almost all the natural phenomena. When we say that a body has energy, we mean that it can do work, so it possesses energy. The energy of running water can we used the water mills or water turbines.
Fossil fuels are known as non-renewable resources because it took millions of years for them to attain the present form.
Solar energy is the most preferred. Solar energy is the energy coming from the sun and is used directly and indirectly. Sunlight does not pollute the environment in any way. The sunrays are the ultimate source of life on Earth. We are dependent on the sun for all our food and fuels. If we find a suitable method to use a fraction of the solar energy reaching the Earth, then it would be enough to fulfill our energy requirement.
i. An electric motor converts electrical energy to mechanical energy
ii. Drill machine
iii. Electric fan
iv. Electric spinner
v. Electric grinder
An electric generator converts mechanical energy into electrical energy.
(i) Efficiency = required form of output / total input energy
(ii) % Efiiciency = required for of out put / total input energy x 100
Let a body of mass m be raised through height h from the ground. The body will acquire potential energy equal to the work done in lifting it to height h. Thus,
Potential Energy P.E. = F x h
= w x h
(Here weight of the body = w = mg)
P.E. = wh = mgh …………. (i)
Thus, the potential energy possessed by the body for the ground is mgh and is equal to the work done in lifting it to height h.
Energy cannot be destroyed however it can be converted into some other forms.
Rub your hands together quickly. You will feel them warm. You have used your muscular energy in rubbing hands as a result heat is produced. In the process of rubbing hands, mechanical energy is converted into heat energy.
A pole vaulter uses a flexible vaulting pole made of special material. It is capable to store all the vaulter’s kinetic energy while bending to the form of potential energy. The vaulter runs as fast as possible to gain speed. The kinetic energy gained by the vaulter due to speed helps him/her to rise as the vaulter straightens. Thus he attains height as the pole returns the potential energy stored by the vaulter in the pole.
The energy possessed by a body both due to its motion or position is called mechanical energy. e.g. water running down a stream, a moving car, a lifted hammer, a stretched bow, a catapult, or a compressed spring, etc. Possesses mechanical energy.