Unit of Work - Definition, Formula, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:40 PM IST

Work is defined as the extent to which an object or a point is moved. Some frequent examples of force are to cycle on a mountain bike or carry something with the gravity of the earth.
Mathematically, work is represented as follows;
W = Fd cos(θ)
Where ,
F is force applied
And d is the displacement

Also read -

How to measure work done? Or definition of work measure

We regard work as a synonym for effort, labour, exertion or energy invested in our everyday lives. The term work, however, is completely distinct in Physics from all of these terms.

The work carried out is measured as in Joules(J). The work is calculated by multiplying the force by object's displacement.

W = F. S.

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How to measure work done? Or definition of work measure
Unit of work-
What is the SI unit of Work?

Unit of Work - Definition, Formula, FAQs

Unit of work-

In SI: Kg m² s⁻²The basis unit

The MKS unit here is Kg m²s⁻².

The meter-kilogram-second is called MKS

Also Read:

What is the SI unit of Work?

The SI work unit is Joule (J). Joule is defined as the work of a newton, which causes a one meter displacement. The newton meter (N-m) can sometimes be used as a measurement method.

Dimensional Formula Of Work

ML²T⁻²provides the dimensional formula.

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NCERT Physics Notes:

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

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Frequently Asked Questions (FAQs)

1. What is a work unit defined?

Work unit and its definition. Work unit is Joule. 1 joule is the work done if 1 Newton moves the body in the direction of force by a distance of 1 meter.

2. What is the formulation work done?

The concept of work carried out in W equates, mathematically, to force f times the distance (d), which is W = f. d, and, if it is applied in angle θ − due to the shift, then work done in W = f.dcos θ

3. If maximum and minimum work is done?

The work being done is minimum as COS 180 is equal to negative one when the force is applied to one direction, while the body's displacement is to the opposite end. This is the least work possible and maximum work is done when the force and displacement is in the same direction.

4. How work is calculated?

Work is done by moving the object by a force applied to the object. The work is determined by multiplying the force by the movement quantity of the item (W=F*d). There is 30 n-m of work by a force of 10 newtons moving an object for 3 m.

5. Is work a scalar quantity?

Work is a quantity scalar which is made up of two quantities of vectors.

6. What is the definition of work in physics?

In physics, work is defined as the transfer of energy that occurs when a force acts upon an object and causes it to move in the direction of the force. It's important to note that work is only done when both force and displacement are present and in the same direction.

7. What is the formula for calculating work?

The formula for work is W = F * d * cos(θ), where W is work, F is the applied force, d is the displacement of the object, and θ is the angle between the force and displacement vectors. When the force is parallel to the displacement, cos(θ) = 1, simplifying the formula to W = F * d.

8. Is work done when an object is held stationary?

No, work is not done when an object is held stationary, even if a force is applied. This is because work requires both force and displacement. If there's no displacement, no work is done, regardless of the force applied.

9. Can work be done by a perpendicular force?

No, a force perpendicular to the direction of motion does not do any work. This is because the angle between the force and displacement vectors is 90°, and cos(90°) = 0, making the work done equal to zero in the work equation.

10. Can work be negative?

Yes, work can be negative. This occurs when the force applied is in the opposite direction of the object's motion. For example, when you're slowing down a moving object, the work done by the opposing force is negative.

11. What is the significance of work in the context of simple machines?

In simple machines, the concept of work helps explain mechanical advantage. While these machines can't create energy, they can trade force for distance, allowing a smaller input force to move a larger load over a greater distance, with the work done remaining constant.

12. Can work be done by multiple forces simultaneously?

Yes, multiple forces can do work on an object simultaneously. The net work done is the sum of the work done by each individual force. This is why we often calculate the net force before determining the work done in complex systems.

13. How does the concept of work apply in rotational motion?

In rotational motion, work is done by torque causing angular displacement. The formula becomes W = τ * θ, where τ is torque and θ is the angular displacement. This is analogous to the linear work formula, with torque replacing force and angular displacement replacing linear displacement.

14. How does mass affect the work done?

Mass doesn't directly appear in the work equation (W = F * d), but it affects the force required to move an object. More massive objects require more force to achieve the same acceleration, potentially increasing the work done.

15. How does the angle of incline affect work done against gravity?

On an incline, the work done against gravity is W = mgh, where h is the vertical height gained, not the length of the incline. The angle of incline affects the force required to move the object, but not the total work done against gravity.

16. What are the SI units for work?

The SI unit for work is the joule (J). One joule is equal to the work done when a force of one newton causes a displacement of one meter in the direction of the force.

17. How does the concept of work apply in thermodynamics?

In thermodynamics, work is one way that a system can exchange energy with its surroundings. It's often associated with changes in volume, such as the work done by a gas expanding against a piston.

18. What's the difference between work and energy?

Work is the process of transferring energy, while energy is the capacity to do work. When work is done on an object, energy is transferred to or from that object. Energy exists in various forms, while work is specifically the transfer of energy through force and displacement.

19. How is work related to power?

Power is the rate at which work is done or energy is transferred. Mathematically, power is work divided by time (P = W / t). So, while work measures the total energy transferred, power measures how quickly that transfer occurs.

20. How does work relate to conservation of energy?

The work-energy principle is a consequence of the conservation of energy. When work is done on a system, it changes the system's energy. If the system is isolated, the total energy remains constant, but energy can be transferred between different forms (e.g., from potential to kinetic).

21. How does friction affect work?

Friction typically does negative work because it acts in the opposite direction of motion. It converts kinetic energy into heat energy, effectively reducing the useful work done by other forces in the system.

22. How does air resistance affect work calculations in projectile motion?

Air resistance does negative work on a projectile, gradually reducing its kinetic energy. This makes the trajectory calculations more complex, as the work done by air resistance depends on factors like velocity, shape, and air density, and varies throughout the motion.

23. What is the significance of negative work in damped oscillations?

In damped oscillations, negative work is done by the damping force, gradually reducing the system's energy. This negative work explains why the amplitude of oscillations decreases over time, eventually bringing the system to rest.

24. What is the relationship between work and information in the context of Maxwell's demon?

Maxwell's demon thought experiment explores the relationship between work, information, and entropy. It suggests that information can be used to extract work from a system, seemingly violating the second law of thermodynamics. This paradox has led to deep insights into the connections between information theory and thermodynamics.

25. How does the concept of work apply in non-equilibrium thermodynamics?

In non-equilibrium thermodynamics, work is associated with the maintenance of gradients (like temperature or concentration) that drive flows of energy or matter. Understanding work in this context is crucial for studying complex systems far from equilibrium, such as living organisms or certain industrial processes.

26. What is the work-energy theorem?

The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy. Mathematically, it's expressed as W_net = ΔKE, where W_net is the net work and ΔKE is the change in kinetic energy.

27. How does gravity affect work?

Gravity can either do positive or negative work depending on the direction of motion. When an object moves downward, gravity does positive work. When an object moves upward, gravity does negative work, as it opposes the motion.

28. What is the concept of zero work?

Zero work occurs when there is no displacement in the direction of the applied force, or when no force is applied in the direction of displacement. Examples include pushing against a stationary wall or carrying a load horizontally at constant speed.

29. What is the relationship between work and potential energy?

Work done against a conservative force (like gravity) is stored as potential energy. For example, when you lift an object, the work done against gravity is stored as gravitational potential energy in the object.

30. What is the significance of the dot product in the work equation?

The dot product in the work equation (W = F • d) accounts for the angle between the force and displacement vectors. It ensures that only the component of force parallel to the displacement contributes to the work done.

31. What is the work done by a spring?

The work done by a spring is given by W = ½kx², where k is the spring constant and x is the displacement from the spring's equilibrium position. This formula represents the area under the force-displacement curve for a spring.

32. What is the difference between positive and negative work?

Positive work increases the energy of the system, while negative work decreases it. Positive work occurs when the force is in the same direction as the displacement, and negative work occurs when the force opposes the displacement.

33. Can work be done by a centripetal force?

No, a centripetal force does not do work. Although it causes circular motion, the force is always perpendicular to the direction of motion. Since the angle between force and displacement is always 90°, the work done is zero.

34. What is the work-kinetic energy theorem?

The work-kinetic energy theorem states that the work done by the net force acting on a particle is equal to the change in the particle's kinetic energy. It's expressed as W_net = ½mv²_final - ½mv²_initial, where m is mass and v is velocity.

35. What is the relationship between work and force-displacement graphs?

The work done by a force is equal to the area under the force-displacement graph. For a constant force, this area is a rectangle. For a varying force, like a spring, it's the total area under the curve.

36. What is the concept of virtual work?

Virtual work is a theoretical concept used in mechanics where imaginary, infinitesimal displacements are considered to analyze force equilibrium. It's particularly useful in solving complex statics problems and in the principle of least action in advanced physics.

37. How does work relate to conservative and non-conservative forces?

For conservative forces, the work done is path-independent and can be expressed as the change in potential energy. For non-conservative forces, like friction, the work done depends on the path taken and typically results in energy dissipation.

38. How does the concept of work apply in fluid dynamics?

In fluid dynamics, work is often associated with pressure-volume changes. The work done by a fluid expanding or contracting is given by W = -P * ΔV, where P is pressure and ΔV is the change in volume.

39. What is the relationship between work and impulse?

While work relates force to displacement, impulse relates force to time. Impulse is the change in momentum, while work is the change in energy. Both concepts involve force, but they describe different aspects of motion and energy transfer.

40. How does the concept of work apply in quantum mechanics?

In quantum mechanics, work is related to changes in the expectation values of observables. The quantum work operator is associated with changes in the Hamiltonian of a system, reflecting energy changes at the quantum level.

41. What is the significance of path independence in work calculations?

Path independence is a key feature of conservative forces. For these forces, the work done between two points is the same regardless of the path taken. This allows us to define potential energy functions and simplifies many calculations in physics.

42. What is the concept of work in relativistic physics?

In relativistic physics, the concept of work must account for the equivalence of mass and energy (E = mc²). The work done on a particle can change its kinetic energy and its rest mass, leading to more complex relationships between work, energy, and momentum.

43. How does the concept of work apply in electromagnetism?

In electromagnetism, work is done when charges move in electric or magnetic fields. The work done by an electric field on a charge is W = qV, where q is the charge and V is the potential difference. In magnetic fields, work is done on current-carrying conductors.

44. What is the relationship between work and heat in thermodynamics?

In thermodynamics, work and heat are two ways of transferring energy between a system and its surroundings. The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system.

45. How does the concept of work apply in astrophysics?

In astrophysics, work is often considered in the context of gravitational fields. For example, the work done to escape a planet's gravitational field is equal to the change in gravitational potential energy. This concept is crucial in understanding orbital mechanics and space travel.

46. How does the concept of work relate to energy barriers in chemical reactions?

In chemical reactions, work is related to the energy barrier (activation energy) that reactants must overcome. The work done to overcome this barrier determines the rate of the reaction. Catalysts work by reducing this energy barrier, effectively reducing the work required for the reaction to proceed.

47. What is the relationship between work and torque in rotational dynamics?

In rotational dynamics, work is done by torque causing angular displacement. The formula W = τ * θ is analogous to the linear work formula, with torque replacing force and angular displacement replacing linear displacement. This relationship is crucial in understanding the energetics of rotating systems.

48. How does the concept of work apply in quantum field theory?

In quantum field theory, work is associated with changes in the energy states of fields. The creation and annihilation of particles, which are excitations of these fields, involve energy changes that can be interpreted as work done on or by the field.

49. What is the significance of work in the context of energy harvesting technologies?

In energy harvesting technologies, the goal is to extract useful work from ambient energy sources. Understanding the concept of work is crucial in designing efficient systems that can convert various forms of energy (like vibrations, heat, or light) into usable electrical energy.

50. How does the concept of work apply in statistical mechanics?

In statistical mechanics, work is related to changes in the macroscopic parameters of a system. The work done on a system can change its microstate distribution, affecting thermodynamic properties like entropy. This connection between microscopic states and macroscopic work is fundamental to understanding the behavior of large systems.

51. How does the concept of work apply in the theory of relativity?

In relativity, work must be considered in the context of spacetime. The relativistic work-energy theorem relates the work done on a particle to changes in its relativistic energy, which includes both kinetic energy and rest energy. This leads to corrections in the classical formulas for high-speed particles.

52. What is the significance of work in the context of quantum tunneling?

In quantum tunneling, particles can pass through energy barriers that they classically shouldn't be able to overcome. While no classical work is done, the concept of work helps in understanding the probability of tunneling and its applications in technologies like scanning tunneling microscopes and nuclear fusion.

53. What is the relationship between work and entropy production?

Work and entropy production are closely related in irreversible processes. When work is done on a system in a non-ideal way, some energy is always lost to entropy production. This relationship is fundamental to understanding the efficiency limits of real-world processes and machines.

54. How does the concept of work apply in the study of black holes?

In the context of black holes, work is related to changes in the black hole's mass-energy. The work done to compress matter into a black hole increases its mass and surface area. Understanding this helps in studying phenomena like Hawking radiation and the thermodynamics of black holes.

55. What is the significance of work in the context of quantum computing?

In quantum computing, the concept of work is related to the energy required to manipulate quantum states. Understanding and minimizing this work is crucial for developing efficient quantum algorithms and maintaining the coherence of quantum systems. This connects the classical concept of work to the quantum realm, bridging fundamental physics and cutting-edge technology.