Work done Definition and 1000 Threads

In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, it is often represented as the product of force and displacement. A force is said to do positive work if (when applied) it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.
For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). When the force F is constant and the angle between the force and the displacement s is θ, then the work done is given by:




W
=
F
s
cos


θ



{\displaystyle W=Fs\cos {\theta }}
Work is a scalar quantity, so it has only magnitude and no direction. Work transfers energy from one place to another, or one form to another. The SI unit of work is the joule (J), the same unit as for energy.

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  1. B

    Work done and total heat transfer for piston-cylinder device

    Hi everybody, this question is on an old exam paper given to us for exam prep purposes. No answers have been supplied however. Am I on the right track? Question: A mass of 0.2kg of saturated refrigerant-134a is contained in a piston-cylinder device at 200kPa. Initially 75% of the mass is in...
  2. S

    Calculating Power and Work Done for a Punch

    can i say the work done on the punch of frighter??, i mean the force of the punch and the distance traveled by the punch. example, the force of punch is 100N and the distance for punch from the body to hit the target is 0.5m. work done = 100 X 0.5m = 50J and the power of the punch is...
  3. M

    T: What is the net work done by an Otto engine?

    Homework Statement Show that the net work done by the otto engine per cycle is Cv(Tc - Tb)(1 - Ta/Tb) PV diagram: [PLAIN]http://www.antonine-education.co.uk/physics_a2/options/module_7/topic_4/Otto_indic.gif Homework Equations Work done by a kmole of gas expanding irreversibly and...
  4. O

    Work done against gravity on a right circular cone

    Homework Statement A right circular cone has vertex down and is 10 feet tall with base radius 5 feet. The cone is filled with a fluid having varying density. The density varies linearly with distance to the top. Here "varies linearly" means the quantities are related by an equation of at most...
  5. O

    Find work done pulling sled with rope

    Homework Statement A loaded sled is pulled by means of rope that makes an angle of 45 with the horizontal. If the mass of the sled is 60 kg and the coefficient of friction is .0200, how much work is done in pulling the sled at constant velocity along a level road for a distance of 1.00 km...
  6. A

    How do you calculate the work done against gravity?

    Please help me ! If a 3.0j of work is done in raising 175 g apple , how far is it lifted?
  7. P

    Work Done by Gas in Carnot Cycle

    Hi, I was thinking about the isothermal and adiabatic expansions in the Carnot Cycle and I was wondering: In these processes, the gas is doing work. In the adiabatic change, the pressure (force), acts over a distance (expansion) transferring energy (Kinetic Energy) - but this is an adiabatic...
  8. P

    How Is Work Calculated in a Force Field Along a Parametrized Curve?

    Find the work done by the force field F= 3yi - x^2j in moving a particle along the curve y=x^(1/2) from (1,1) to (4,2) so i parameterize and get x=1+3t, y= 1+t so 3(1+t)-(1+t)^2 then take the derivative of x and y and multiple to ge 9(1+t)-(1+t)^2 and i integrate that from...
  9. R

    Speed as a ratio, but what about work done and moments?

    Hi all, Speed is a ratio of the distance traveled per unit time. But what then is work done and moments? For example, work done is force multiplied by the distance traveled in the direction of the force. But how would you explain the rationale of multiplying these two quantities? As...
  10. A

    What is the work done by gas, given V, T and P

    Homework Statement 0.5 m3 of air is located in a vessel. Their temperature is T1=0oC and the pressure is p=3·105. What work will be done when heating the gas with constant pressure (isobaric process) to T2=100oC? Homework Equations I was unable to find any equation regarding to the...
  11. H

    How to find work done in exact values?

    10N force acting in the direction of the vector (1, 1) moves an object from P (-2, 1) to Q (5, 6), calculate the work done. The Attempt at a Solution I can do this question correctly except I only know how to do it using decimals but the answer is in exact values of 60√2J. I can't figure out...
  12. E

    Work done by a distributed force on a string

    Hi All I'd like to know how I could calculate the work done by a distributed force on a string. Let's say the force at a point x at a time t is given by F(x,t). Now the instantaneous amplitude of the string is given by y(x,t), say I think that the work done by the force in...
  13. I

    Work done by liquid's frictional viscosity

    Homework Statement A 0.75 sphere is dropped through a tall column of liquid. When the sphere has fallen a distance of 2.0 m, it is observed t have a velocity of 2.5 m/s. How much work was done by the frictional viscosity of the liquid? PLEASE EXPLAIN-- I really would like to understand this...
  14. D

    How Is Work Calculated in a Vector Field?

    Homework Statement Find the work done by the force field F in moving an object from P to Q. F(x,y,z)=10y^(3/2)i+15x\sqrt{y}j P(1,1), Q(2,9)Homework Equations W = \intF dot drThe Attempt at a Solution I have no clue how to do it
  15. T

    How Does Entropy Change and Work Done Relate in a Reversible Ideal Gas Cycle?

    Figure 20-29 shows a reversible cycle through which 1.00 mol of a monatomic ideal gas is taken. Assume that p = 2p0, V = 2V0, p0 = 1.13*10^5 Pa, and V0 = 0.0235 m^3. Fig. 20-29 http://s1142.photobucket.com/albums/n603/bdoneski/?action=view&current=hrw7_20-29.gif" (a) Calculate the work done...
  16. N

    Calculate Work Done by Ideal Gas

    Homework Statement 1 mole of an ideal gas is at 9 atm pressure, occupies 1 L and has an internal energy of 474 J. The gas is first cooled at constant volume until its pressure is 1 atm. It is then allowed to expand at constant pressure until its volume is 7 L with an internal energy of 766...
  17. P

    No Work Done during Circular Motion

    Hi guys, :smile: Work Done = Force x Distance x cos of Theta - the angle between the Force and the Displacement Vector / direction of motion In Circular motion I know the force but I am given velocity. In order to prove that no work is done is it correct to say the following: If we have two...
  18. P

    How is acceleration = work done?

    Hi :smile: So, let's go straight to the point: a = v - u / t Kinetic Energy: 1/2 mv2 Ok, I understand that a acceleration, a change in velocity, will change the Kinetic Energy since v is part of the Kinetic energy equation. But acceleration is not simply a change in velocity. It is the rate...
  19. E

    How Is Net Work Calculated in a Cyclic Ideal Gas Process?

    Homework Statement An ideal gas follows the three-part process shown in the figure. At the completion of one full cycle, find the net work done by the system. Homework Equations W=P*deltaV; Total Work = Wab+Wbc+Wca A=1/2bh The Attempt at a Solution Work done from C to A is zero, because...
  20. D

    What is the work done by a radial force in this situation?

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  21. V

    How Much Work Is Done in Adiabatic Compression of Gas?

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  22. I

    Work done by the torque on a pulley

    Homework Statement The pulley in the illustration is a uniform disk of mass 2.40 kg and radius 0.220 m. The block applies a constant torque to the pulley, which is free to rotate without friction, resulting in an angular acceleration of magnitude 0.180 rad/s2 for the pulley. As the block falls...
  23. Z

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  24. G

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  25. G

    Find Work Done on 230 kg Crate in 12 m Displacement

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  26. D

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  27. N

    Find work done draining water from a tank

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  28. B

    Calculating Work Done by a Variable Force in an Electric Elevator

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  29. P

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  30. C

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  31. Q

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  32. A

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  33. Y

    Calculating Work and Energy for a Cyclist Riding Up a Slope

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  34. 5

    What is the force required and amount of work done to stop this motion?

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  35. N

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  36. R

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  37. J

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  38. M

    Work done on a stationary bike

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  39. E

    Work in Pulley System: What is the Total Work Done on the 20.0-N Block?

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  40. A

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  41. A

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  42. J

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  43. C

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  44. X

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  45. E

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  46. M

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  47. F

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  48. A

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  49. M

    Electrostatics - Work done by an electron

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  50. D

    Problem on work done in thermodynamics

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