Energy transformed work done applied force x distance. If you lift a suitcase to place it in its compartment, we say that you are doing work. Chapter 5 work, energy and power 012214 ib physics ic nl 1 2. Workenergy relationship the work done by the net force. To determine the energy burned during that exercise. Cbse ncert solutions for class 11 physics chapter 6. In an inelastic collision, the final kinetic energy is always le energy of the system. Pump a b 30o 100 ft 55 ft 20 ft 48o hill if the pumps power output is 250 horsepower, how long will it take to pump all 3000 gallons to reservoir b. Mathematically, power wt where w work done, t time taken.
But joule is the unit of work and its also the unit of energy. Exploring an abandoned missile engine test site duration. A massive truck traveling along the highway at a high speed has much kinetic. Energy, work, and power and the related units of measure.
So, if two forces each do 10 j of work, but force f 1 does this work in 1 minute while f 2 does it in two minutes, f 1 has more power because it did the same work in less time. Power is the rate of doing work, so the units are joules per second watts. A force of 20 newtons pushing an object 5 meters in the direction of the force does 100 joules of work. Energy is a key principle in physics, as it allows work to be done. Work is defined as the product of the force and the distance covered by the body in the direction of force. Power and work lab purpose to determine the work and power required to walk and also to run up one floor of stairs. This is the name used to describe stored energy that an object has because of its position in this case, higher above the surface of the earth. The units of work are of two types absolute units gravitational units joule s. Answers, with formula when needed will be recorded on the whiteboards at each team table. In this article, we will learn all about the concept of work, power and energy. Applicants are to note that the application process is complete. Compute the work done by the applied force in 10 s, work done by friction in 10 s.
A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 n on a table with coefficient of kinetic friction 0. Download work energy power problems with solutions. Remember the average ke of molecules is temperature. This is a theorem, ie a tautology because it is only true by definition of ke and by newton 2. And ill do another presentation on all of the things that soon. You must have energy to accomplish work it is like the currency for performing work.
Introduction to work and energy video khan academy. The work done in the motion of a body over a closed loop is zero for a conservation force only. Phys068 energy, work, and power revised \ch01 energy work, and power scofield supplemental notes september 8, 2009 page 1 of 12 chapter 1. General mechanicswork and power wikibooks, open books. If a person is pushing a box inside a moving train, the work done in the frame of train will. The work done by the net force acting on a body is equal to the change in the bodys kinetic energy. If you put energy into an object, then you do work on that object. This document is highly rated by class 9 students and has been viewed 6802 times. Kinetic energya moving object can do work on another moving object it strikes and can thus move that object, therefore w is done. Because if you look at the definitions that wikipedia gave us, work is energy transferred by a force and energy is the ability to work. A farmer ploughing the field, a construction worker carrying bricks, a student studying for a competitive examination, an artist painting a beautiful landscape, all are said to be working. If we are using one kw of power, a kwh of energy will last one hour.
For the spring and gravity, when we change the direction of the displacement the force doesnt change direction, so the sign of the work done changes, so, round a closed path, the work done is zero. Work, energy and power definition, units, formula, examples. If w, f and s indicate work, force and displacement respectively then the work is given by the following formula. Find the frictional force and use the work energy principle.
Work, energy and power are the most used terms in physics. The law of conservation of energy says that energy can neither be created nor destroyed but may be transferr ed from one object to another or from one form to another. E can be derived using the equation of motion with constant acceleration to the work done. Work, energy and power class 9 science notes khullakitab. Energy, work, and power energy is a very important concept both in physics and in our world at large. In this post, i am sharing an assignment on work energy power portion of jee physics class 11 portion as per requests received from students. This oer repository is a collection of free resources provided by equella. Work can be done at various rates, or energy can be changed at various rates. During this process, the force on the cycle due to the road is 200 n and. K, energy possessed by a body by virtue of its motion. If 1 joule work is done in 1 sec then it is called 1 watt. Lets have a look at the ideas we already have about work, power and energy. If you continue browsing the site, you agree to the use of cookies on this website.
Work, energy and power gcserevision, physics, forces. Work done by the force is positive if the angle between force and displacement is acute 0 done by a resultant force is equal to the change in kinetic energy that it produces. Jul 24, 2018 class 11 physics chapter 6 work, energy and power 03 work energy theorem iit jee neet duration. They are probably the first thing you learn in your physics class. Work, power and efficiency work, power and efficiency. Power the power is defined as the work done over a time period or rate of work done is known as the power. Work, energy and power tuesday february 10th reading. Work force x parallel distance arizona state university. Power p the rate at which work is done or energy is expended. Class 11 physics chapter 6 work,energy and power 03 work energy theorem iit jee neet duration. A rollercoaster at the top of a slope has stored energy, which is called gravitational potential energy gpe, or sometimes potential energy pe. This ncert class 11 physics chapter 6 work, energy, and power explains the terms work, energy, and power with easytounderstand examples. Work, energy and power class 8 science notes khullakitab. For conservative force 1 work done is independent of the path 2 work done in a closed loop is zero 3 work done against conservative force is stored is the form of potential energy 4 all the above 2.
Physclips ch 7 definition of work definition of kinetic energy. Work, energy and power key concept energy is the ability to do work, and may be obtained in many forms. Theory in this lab you will examine three physical quantities. If we think about appliances like a refrigerator, a dryer, a light bulb which. Work done is generally referred in relation to the force applied while. Energy is the capacity of a physical system to perform work. Work energy transferred to or from an object by means of a force acting on the object. Work done by gravity is positive, by spring and friction is negative. The time rate of work done by a body is called its power. If under a constant force f a body is displaced through a distance s in time t, the power.
In the majority of processes in which there is an energy exchange andor work is done an important factor is the time taken in the process. In both cases you are doing same work but at different rates. If an object is standing still, and you get it moving, then you have put energy into that object. Let us assume the variable force works from position xi to xf then according to the workenergy theorem the change in the kinetic energy is equals to the work done.
Work, power and efficiency work, power and efficiency aqa. Work definition of work work is the transfer of energy. Do work against friction, but cant recover this energy mechanically. Energy, work, and power oberlin college and conservatory. In other words, power is a measure of how quickly work can be done. You can walk up stairs or you can run upstairs in one floor. Two springs have their force constants k1 and k2 and they are stretched to the same extension. If w, f and s indicate work, force and displacement respectively then the work is given by the.
Power is the rate at which work is done, or energy is used. This means it fits the definition for energy and is usually thought of as the energy of moving objects. Product of magnitude of force and the magnitude of displacement of the body during time in which force acts is called work. The rate at which the energy is changed, or work is done is called power p. Work, power and energy practice problems work and power problems 1 how much work will you do if you push a block of concrete 4. Class xi chapter 11 work energy and power physics question 6. The amount of energy transferred is called the work done on the object. Work energy power iit level problems vineet loomba. Energy the capacity to do work scalar types of energy. Energy associated with the state of motion of an object. The examples based on this are very easy and can be seen even in day to day life. Ability to do work by virtue of position or condition. Plaza january 14, 2015 slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising.
F x ma x d v v v v axd ax 2 2 2 0 2 2 0 2 work done by the force energy. The assignment covers topics namely kinetic and potential energy. The rate at which energy is transferred is called power and the amount of energy that is usefully transferred is called efficiency. Work done is said to be one joule, when 1 newton force displaces the body through 1 meter in its own direction. Power is a step further which defines the rate of change of energy flow. Doing work either transfers energy from one object to another or transforms it from one form to another. Work can be thought of as the process of transforming energy from one form into another. Power has many uses in everyday language, but in physics, power specifically means the rate at which work is done. How much work is done pumping 3,000 gallons of water from reservoir a to reservoir b over the hill.
So, if two forces each do 10 j of work, but force f 1 does this work in 1 minute while f 2 does it in two minutes, f 1 has more power because it did the same work in less time power is represented by the capital letter p, and is measured in watts, w note that the symbol. Work and energy can be considered as two sides of the same coin. The energy lost by a system is exactly equal to the work done by the system. Similarly, if you decelerate an object, you decrease its kinetic energy. For these two orbits, determine whether the kinetic energy of the satellite changes during the motion. Work, power and energy all of us use words like work, power and energy. Work, energy, power chapter 7 in a nutshell new concept. Chapter 7 kinetic energy, potential energy, work i. Let us assume the variable force works from position x i to x f then according to the work energy theorem the change in the kinetic energy is equals to the work done on by the variable force. Work, energy and power study material for iit jee askiitians. The workenergy theorem states that the work done on an object is equal to the. Work is said to be done if a force, acting on a body, displaces the body through a certain distance and. In the diagram below, the spring has a force constant of 5000 nm, the block has a mass of 6.
The work done by a resultant force is equal to the change in kinetic energy that it produces. Power the rate at which work is done the rate at which energy is expended p w t work time units j s joule s watt w k. Force in direction of motion is what matters figure 73 force at an angle to direction of motion. Work is given by the force multiplied by the displacement through which the force acts, or. Kinetic energy table 71 typical values of work work is force times distancebut. Calculate the work done by a 47 n force pushing a pencil 0. Work is said to be done if a force, acting on a body, displaces the body through a certain distance and the force has some component along the displacements. Kinetic energy the work capacity of an object due to its motion is called kinetic energy k. Determine the compression of the spring such that the block just makes it to the top of the hill. However, energy is only transferred if the object moves. Mathematically work done is defined as the dot\scalar product of force and displacement, thus it is a scalar quantity. Work done w is defined as the dot product of force f and displacement s. Work is done by a force f on mass m when the force and the displacement.
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