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What Is The Definition Of Work In Physics

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Work For Force At An Angle

Definition of Work in Physics

When force is not applied at 0 degrees , use simple trigonometry to find the work done on that object. You need only know how to use cosine and sine for introductory-level problems.

For example, imagine the dog in the above situation standing on the edge of a cliff, so that the rope between the child and the dog makes an angle of 45 degrees with the horizontal snowfield. If the dog applies the same force as before at this new angle, you find that the horizontal component of this force is given = 14.1 N, and that the resulting work done on the sled is = 176.8 J. The new acceleration of the child is given by the value of the force and Newton’s law, F = ma: /20 kg) = 0.71 m/s2.

Work Power And Energy Questions

  • What is the relationship of work energy and power?
  • What happens to the energy as work is done?
  • What is the difference between work energy and power?
  • Is energy transferred the same as work done?
  • How does work affect an objects energy?
  • How is work energy and power related to each other?
  • How are force energy and work related?
  • What is the formula of work energy and power?
  • How do you calculate energy from power?
  • Can force be converted into energy?
  • Classification Of Energy Sources In Physics

  • Renewable sources: Energy sources that can be renewed again and again are known as Renewable Sources. They are available in very large amounts as a result probably they will never execute. For example Sun, Biomass, water, wind, wood etc.
  • Non-renewable sources: Energy sources that cannot be used again and again are renewable sources of energy. In short they are available in Limited quantity and they will execute one day. These are the conventional source which are decreasing with the time and cannot be replenished or renewed for further use. These sources are called exhaustible resources. Mineral sources are like fossil fuels, nuclear fuels and non renewable sources
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    Work Force And Energy

    * Work is the measure of a quantity that is capable of accomplishing Macroscopic Motion of a System due to the action of a Force over a Distance.* Force is the agent of change, and Work is a measure of the change.* The Force does the Work, not the agent that created the Force. Do not confuse the work you do to create a force with the work done by the force you create they are not the same. The force you exert holding a 100 pound barbell above your head does no work on the barbell while the barbell is at rest, but you do work to create that force.* Work is related to the distance a force moves an object and not the time it takes to move the object. * A Force does no work unless the system is free to move “along the direction” of the Force applied. When a Force and the object’s displacement are perpendicular, the work done by the force is zero.* The Energy transferred into a system by the action of a Force is the Work done on the System.* If system A does work then energy flows out of the system A. If another system does work on system A then energy flows into the system A from the other system.* There is no such thing as pure energy. Energy is a property of a system which depends upon the system’s mass and speed, and sometimes on its position.* Mass and Energy have much in common. Einstein’s famous equation E = mc2 shows that mass is itself a form of “stored” energy.* Energy is a scalar quantity. Like mass, it has no direction associated with its magnitude.

    How To Calculate Work

    Work: The Scientific Definition

    You can calculate total work by adding up the amount of work done by different forces in a problem. In all cases, calculating work requires a complete understanding of the vectors in the problem, not merely the numbers that go with them. You will need to put basic trigonometry to use.

    • Note: In real life, when a force acts on an object besides gravity, it is unlikely to be constant. Any force F you see mentioned in these examples can be assumed to be a constant force. When forces vary, the relationships noted here remain valid, but you will need to perform integral calculus to solve the associated problems.

    Example: A dog pulling a 20-kg child-sled combination across a horizontal snowfield accelerates from rest to a velocity of 5 m/s over the course of 5 seconds . How much work does the dog do on the child-sled combination? Assume friction is negligible.First, you calculate total force applied by the dog to the child and sled: F = ma = = 20 N. Displacement is average velocity /2 multiplied by time t , which is 12.5 m. Thus total work is = 250 J.

    • How would you solve this problem using the work-energy theorem instead?

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    What Is Work In Physics

    Work Physics Definition:When a force acts on an object such that it displaces through some distance in the direction of applied force, then the work is said to be done by the force.

    We are giving a detailed and clear sheet on all Physics Notes that are very useful to understand the Basic Physics Concepts.

    General Derivation Of The Workenergy Theorem For A Particle

    For any net force acting on a particle moving along any curvilinear path, it can be demonstrated that its work equals the change in the kinetic energy of the particle by a simple derivation analogous to the equation above. Some authors call this result workenergy principle, but it is more widely known as the workenergy theorem:

    v . }}= \cdot \mathbf )}}= }}\cdot \mathbf +\mathbf \cdot }}=2 }}\cdot \mathbf =2\mathbf \cdot \mathbf .}

    The remaining part of the above derivation is just simple calculus, same as in the preceding rectilinear case.

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    Work Of Forces Acting On A Rigid Body

    The work of forces acting at various points on a single rigid body can be calculated from the work of a resultant force and torque. To see this, let the forces F1, F2 … Fn act on the points X1, X2 … Xn in a rigid body.

    The trajectories of Xi, i = 1, …, n are defined by the movement of the rigid body. This movement is given by the set of rotations and the trajectory d of a reference point in the body. Let the coordinates xii = 1, …, n define these points in the moving rigid body’s reference frameM, so that the trajectories traced in the fixed frame F are given by


    Coasting Down A Mountain Road

    Work and Energy : Definition of Work in Physics

    Consider the case of a vehicle that starts at rest and coasts down a mountain road, the workenergy principle helps compute the minimum distance that the vehicle travels to reach a velocity V, of say 60 mph . Rolling resistance and air drag will slow the vehicle down so the actual distance will be greater than if these forces are neglected.

    Let the trajectory of the vehicle following the road be X which is a curve in three-dimensional space. The force acting on the vehicle that pushes it down the road is the constant force of gravity F = , while the force of the road on the vehicle is the constraint force R. Newton’s second law yields,

    ft . }=8.3}},\quad }\quad s=8.3}}\approx 2000}.}

    This formula uses the fact that the weight of the vehicle is W = mg.

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    Work Done By A Variable Force

    Calculating the work as “force times straight path segment” would only apply in the most simple of circumstances, as noted above. If force is changing, or if the body is moving along a curved path, possibly rotating and not necessarily rigid, then only the path of the application point of the force is relevant for the work done, and only the component of the force parallel to the application point velocity is doing work . This component of force can be described by the scalar quantity called scalar tangential component , where is the angle between the force and the velocity). And then the most general definition of work can be formulated as follows:

    Work of a force is the line integral of its scalar tangential component along the path of its application point.
    If the force varies we need to use calculus to find the work done. If the force is given by F then the work done by the force along the x-axis from a to b is:

    as presented above.

    Notice that only the component of torque in the direction of the angular velocity vector contributes to the work.

    Physics: Work And Energy

    When an object moves towards the direction of the force applied, then work is said to be done. But for work to be done energy is the most important thing as it is the ability to work. When work is done by animals or humans, they get the energy from food and when work is done by machines, they get energy from electricity or fuel.


    Work is done when a force produces some kind of motion. For example, when a man climbs a mountain, work is done because while climbing a mountain he is moving against the force of gravity. Hence, work depends upon two factors. They are:

    • Magnitude of force

    • The direction in which the body moves due to the force applied.

    Hence, work is measured by the product of displacement and force of a body along with its direction of the force. It is referred to as scalar quantity and the SI unit of work is Joule.

    The equation thus stands as:

    Work = F * S

    If a body is displaced by S while a Force F acts on it, in such a case

    Work W = FS Cos

    One thing to note here is that force is said to work when it produces a motion in an object. For example, a man tries to move a wall but the wall does not move, hence the work done by the man is zero as there is no displacement produced. But he does lose energy because in his attempt to push the wall he stretches his muscles and thus feels tired.


    The formula of kinetic energy is \

    Hence from the formula given above, we can state:

    1. The kinetic energy of a body gets doubled whenever its mass gets doubled.

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    What This Chapter Is All About

    Work Energy and Power are the most important terms used in Physics that the students learn in school early on. Work and energy are the two sides of a coin as both are interconnected to each other. Work is referred to as the displacement of an object when a force is applied to it while energy is referred to as the capacity to do the work. It exists in various forms like potential, kinetic, chemical, thermal, nuclear, electrical energy and so on. Power is the work done per unit of time. Studying work energy power is important in terms of both acquiring knowledge and getting higher marks in the exam.

    Work Has Units Of Energy

    4.1 Work: the scientific definition By OpenStax

    The total energy of a system is its internal or thermal energy plus its mechanical energy. Mechanical energy can be divided into energy of motion and “stored” energy . The total mechanical energy in any system is the sum of its potential and kinetic energies, each of which can take various forms.

    Kinetic energy is energy of motion through space, both linear and rotational. If a mass m is held a distance h above the ground, its potential energy is mgh. Where the acceleration due to gravity, g, has the value of 9.80 m/s2 near Earth’s surface.

    If the object is released from rest at height h and allowed to fall downward to Earth , its kinetic energy at impact is mv2 = mgh, as all of the energy has been converted from potential to kinetic during the fall . At all times, the sum of the potential energy of the particle and its kinetic energy remains constant.

    • Because force has units of newtons in the SI system and distance is in meters, work and energy in general have units of kgm2/s2. This SI unit of work is known as the Joule.

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    Derivation For A Particle In Constrained Movement

    In particle dynamics, a formula equating work applied to a system to its change in kinetic energy is obtained as a first integral of Newton’s second law of motion. It is useful to notice that the resultant force used in Newton’s laws can be separated into forces that are applied to the particle and forces imposed by constraints on the movement of the particle. Remarkably, the work of a constraint force is zero, therefore only the work of the applied forces need be considered in the workenergy principle.

    To see this, consider a particle P that follows the trajectory X with a force F acting on it. Isolate the particle from its environment to expose constraint forces R, then Newton’s Law takes the form

    . }v^,\quad }\quad v=}.}

    Notice that this formula uses the fact that the mass of the vehicle is m = W/g.

    Is Power A Scalar Quantity

    Power is a scalar quantity because it is a ratio of two scalar quantities.

    Watch this fun and engaging rapid fire session based on the topic Work, Energy and Power!

    Work, Power and Energy is one of the important topics of JEE Main and JEE Advanced, watch the video and understand the type of questions asked from this topic!

    Stay tuned to BYJUS and Fall in Love with Learning!

    Put your understanding of this concept to test by answering a few MCQs. Click Start Quiz to begin!

    Select the correct answer and click on the Finish buttonCheck your score and answers at the end of the quiz

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    What Is The Definition Of Work Done

    How to define work done in physics?

    The definition of work done in physics refers to both the force applied to the body and the displacement of the body.

    Consider a block on a horizontal frictionless surface. A constant force F is acting on this block. The action of this force is to drive the body in a straight line in the direction of force over a distance d.

    W= F x d

    Where F is the force acting on the block and d is the displacement of the block.

    The product of the magnitude of the applied force and the distance travelled by the body equals the work done by this force.

    If the force acting on the block is constant, but the force’s direction and the displacement induced by it are not the same. Force F acts at an angle to the displacement d in this case. Fcos is the affective component of force along the displacement direction, and it is this component of a force that causes the block to move in the given direction.

    There work done by the force F acting at an angle to the displacement d is given by,

    W = F x cos x d

    Work: Definition And Formula

    What is Work in Physics | Definition of Work & Work Formula | Physics Basics Concepts

    Work is said to be done when the force acts on an object, which displaces it in the direction of the force.

    Work Definition in Physics: The work done by a force acting on an object is equal to the product of the force and the displacement in the direction of the force.

    Work done \\) is the product of the force \\) and the displacement \\) in the direction of the force. Thus, the work done can be calculated by the below formula,

    \If the displacement is not in the direction of force and, it is making an angle \ with the direction of force, then work can be written as,

    where, \ is the angle between the force and the displacement.

    Practice Exam Questions

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    Why Is Physics Important

    Physics includes the study of astronomy, and in many ways, astronomy was humanity’s first organized field of science. Ancient peoples looked to the stars and recognized patterns there, then began using mathematical precision to make predictions about what would happen in the heavens based on those patterns. Whatever flaws there were in these specific predictions, the method of trying to understand the unknown was a worthy one.

    Trying to understand the unknown is still a central problem in human life. Despite all of our advancements in science and technology, being a human being means that you are able to understand some things and also that there are things you do not understand. Science teaches you a methodology for approaching the unknown and asking questions that get to the heart of what is unknown and how to make it known.

    Physics, in particular, focuses on some of the most fundamental of questions about our physical universe. Pretty much the only more fundamental questions that could be asked fall in the philosophical realm of “metaphysics” , but the problem is that these questions are so fundamental that many of the questions in the metaphysical realm remain unresolved even after centuries or millennia of inquiry by most of history’s greatest minds. Physics, on the other hand, has resolved many fundamental issues, even though those resolutions tend to open up whole new types of questions.

    For more on this subject, check out “Why Study Physics?” .

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