What is Work done: Definition and 1000 Discussions

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. K

    How Is Work Calculated in Thermodynamic Processes?

    Homework Statement Homework Equations no The Attempt at a Solution [/B] I assumed the path from c to a to be a straight line and I'm unable to find the work as the area in the image above. (sorry my poor english). The book's answer is -2460 J. The answer I found is ≅ -1112 J. My...
  2. Y

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    Homework Statement A metallic sphere is placed inside a hollow spherical shell. The potential on the inner and outer spheres is 10 V and 5 V respectively. What is the potential at the center?(The spheres are concentric.) Homework Equations $$V =\frac{kq}{r}$$ The Attempt at a Solution The...
  3. K

    Solving a Physics Problem: Work Done by OR on a Gas

    Homework Statement Homework Equations no The Attempt at a Solution no Since the problem asks how much work was done by OR on the gas, I did not understand why the book's answer is 162 J instead ±81 J that I've found. (sorry my bad english) Sorry, the correct question on the problem is how...
  4. D

    Work done by and against a force

    What is the difference between work done by a force and work done against a force?How would we calculate the two and what is the mathematical relation between the two. Please help. Thanks.
  5. C

    Work done = 1 N x 1 m = 2 kg 1m2 1.414s-2 = 1 J ? wrong ?

    ~In the vacuum of outer space~ If a rocket motor exerts a force of 1 Newton on a mass of 2 kilograms for 1.414213562 seconds over a distance of 1 meter, how many Joules of work have been done? I thought Work = 1 N x 1 m = 1 kg 1m2 1s-2 = 1 J so Work = 1 N x 1 m = 2 kg 1m2 1.414s-2 = 1 J ? I...
  6. S

    How would I calculate the work done by the gas molecules?

    Homework Statement Hello, I just need help figuring out how to calculate the work done by the gas molecules for my physics homework :) Formula given: W=Px∆V (W=work, P=pressure, and V=volume) What I know: So my calculated volume is 1.7x10^-22m^3. Pressure=0.25 A t m (atmospheric pressure) I...
  7. T

    Understanding Electric Fields and Work Done to Move Charges

    Homework Statement Hello. I am having trouble understanding this particular statement found in one of my textbooks. " Work done to move a charge along a line perpendicular to the field is zero" The Attempt at a Solution Field is a space around a charge where if we place any other charge...
  8. R

    I How Does Observer Motion Affect Calculated Work in Relativity?

    I have seen this calculation on web Let consider that old man displaced the cart from pole A to Pole B on platform. Observers are on platform S & in train S', moving with velocity –V then (let, X-axis is parallel to train direction) 1) When AB (displacement) parallel to the direction of train...
  9. A

    Calculating Pump Power for Steady Water Flow: Work-Energy Theorem Approach

    Homework Statement Water is pumped steadily out of a flooded basement at 5.0 m/s through a hose of radius 1.0 cm, passing through a window 3.0 m above the waterline.What is the pump’s power? Homework Equations Volume and mass flow rates are constant R_v = Av; \quad M_v = \rho A v...
  10. M

    Work done for stationary object

    Say I take a brick and push it and it moves, so work is done and chemical energy in my body is transferred into kinetic energy of the brick, which is then transformed to heat energy due to friction, so I have to keep pushing to transfer more of my chemical energy into kinetic energy of the...
  11. A

    Work done by gravity on fluid in u-tube.

    Homework Statement Two cylinders of base area 4cm2 hold fluid of density 1.30(103). In one the fluid has height .854 and the other has height 1.560. They are then joined and the fluids equalize in height--find the work done by gravity on the fluid. Homework Equations A version of...
  12. M

    Work done negative and positive

    Homework Statement I was just wondering whether the following notes I took on work in physics are accurate? Or have I got my understanding wrong? Note on friction Following from the example of the dragging object above… The object stops because it loses kinetic energy due to friction. How...
  13. Titan97

    Work and Heat Transfer in a Magnetic Field: Conduction Rod on Conducting Rails

    Homework Statement A conduction rod (of mass ##m## and length ##l##) was placed on two smooth conducting rails rails connected by a resistor as shown: (the circuit is placed in ##XY##-plane A constant uniform magnetic field is switched on along ##-Z## direction with magnitude ##B## The rod is...
  14. H

    Work Done by Gas: Ideal Diatomic Process

    Homework Statement A 1.00 mol sample of an ideal diatomic gas at a pressure of 1.00 atm and temperature of 420 K undergoes a process in which its pressure increases linearly with temperature. The final temperature and pressure are 720 K and 1.60 atm. Determine the work done by this gas during...
  15. H

    Fluid - Work done to blow a soap bubble

    Hi everybody, I now encounter some problems when try to solve this: Problem statement: Calculate the work done to blow a soap bubble to radius R. Knowing that the process is isotherm, the atmospheric pressure is H, the surface tension is γ. Solution: $$A = A_{1}+A_{2}$$ In which A1 is the work...
  16. Ummuali

    Finding Work done without mass and friction force

    Homework Statement A box was dragged downward from the state of rest through an inclination 10.0 m at an angle of 25 degree. The speed when the box arrived at the base is 3 m/s. a) what is the coefficient force between the box and the surface? b) how many work is done to move the box downward...
  17. Z

    Work done by a non conservative force

    The work done by a conservative force on a closed curve is zero but why it isn't true for the non conservative force?
  18. D

    Find work done by force given distances and times

    Homework Statement A 1.0 kg body is at rest on a friction-less horizontal air track when a constant horizontal force F acting in the positive direction of an x-axis along the track is applied to the body. A stroboscopic graph of the position of the body as it slides to the right is shown in...
  19. Bhumanyu Arun

    Work Done by Force in First 4 Secs: 0

    1. The position x of a particle moving along x-axis at time t is given by the eqn, t=(√x)+2.,where x is in m and t is in s. Find the work done by force in first 4 sec2. W=F.s=mas I first found out x using the given eqn nd then went blank as there was no force or mass given. But the ans is 0
  20. S

    Work Done by Spring on a Body Sliding down a rod

    1. The Question Unable to find the work done by spring on the object sliding down the rod as shown below: Homework Equations Work Done by Spring Force : -1/2 * KΔx2 --(1) where k = Spring Constant Δx = Change in Spring Length[/B] 3. Where the problem occurred While seeing the solution...
  21. 9

    Finding work done by friction on a box

    1. A box of mass m = 59.0 kg (initially at rest) is pushed a distance d = 83.0 m across a rough warehouse floor by an applied force of FA = 204 N directed at an angle of 30.0° below the horizontal. The coefficient of kinetic friction between the floor and the box is 0.100. Determine the...
  22. B

    Finding Work Done by Gravity on Inclined Crate

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  23. E

    Work done on two cart system with spring

    Homework Statement Two identical 0.50-kg carts, each 0.10 m long, are at rest on a low-friction track and are connected by a spring that is initially at its relaxed length of 0.50 m and is of negligible inertia. You give the cart on the left a push to the right (that is, toward the other cart)...
  24. K

    Work done by motor against gravity

    Homework Statement Homework Equations Conservation of Energy: ∑T1+∑U1-2=T∑2 The Attempt at a Solution ∫[/B](600+2s2)ds - 100*9.8*15 = (1/2)mv2. However, the term of work done by the force is less than the term of work done by gravity! The book has a solution, which is exactly this...
  25. gracy

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  26. V

    How Much Work Is Done Pulling a Wagon at an Angle?

    Homework Statement Kids are pulled 2km around a town in a wagon,The handle of the wagon is on an angle of 30 degrees from horizontal and requires 200N to maintain constant velocity. Determine the amount of work done against non‐conservative forces on this walk. Δx = 2km = 2000m angle θ = 30...
  27. almarpa

    Work done by friction by wheels

    Hello all. I have a doubt about the work done by friction force on a wheels , in two diferent situations: a) In Morin's mechanics book, chapter 5 (page 146) he considers the situation in which a car is braking without skidding. He claims that the friction from the ground on the tires causes...
  28. Elvis 123456789

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  29. S

    Finding work done & temp change by looking at a plot

    Homework Statement Refer to plot attached. Homework Equations (a)Find the work done by a monatomic ideal gas as it expands from point A to point C along the path shown in the figure. (The horizontal axis is marked in increments of 25 m3.) (b) If the temperature of the gas is 215 K at point A...
  30. P

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  31. R

    Work done by a person lifting and then throwing a ball

    If I lift a ball of mass 5 kg from ground level to 1.5 meters above ground level and then throw it from this point up to a height of 10 meters, what is the work done by me on the ball? Is the following the correct way to solve this problem? Person only applies force to the ball for 1.5 meters...
  32. K

    Is Work Done by Different Forces Path-Dependent?

    can you help me check if these two statements are true? 1. work done by non-dissipative force is independent of the path that it takes ( ie: gravity) 2. work done by dissipative force is dependent of the path that it takes (ie: friction) Huge thanks!
  33. M

    Work done in vertical springs & External Agent

    Homework Statement I've encountered an answered problem in this book titled, "Physics for Scientists and Engineers with Modern Physics, 9th Ed" by Serway at page 187. So there is a spring which is hung vertically. 1. The first condition was the spring at an equilibrium state (ΔX=0) 2. The...
  34. D

    Work Done: Understanding the Definition and Maths

    I know you guys all understand what work done is defined. I am wonder how work done is defined. Why does it define in this mathematical form? Also, how do we know 1 energy calculated by work formula = 1 energy of other form
  35. F

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    Homework Statement Problem: A sample of dry air has an initial pressure p1 = 1000 hPa and temperature T1 = 300K. It undergoes a process that takes it to a new pressure p2 = 500 hPa with unchanged temperature T2 = T1. Compute the mechanical work per unit mass perfromed by the sample under the...
  36. J

    Finding Work Done from a Graph

    Homework Statement Hi, I am stuck with the following question: The graph (attached) shows how the Moon's gravitational pull F on a lunar lander varies with the distance 'h' from the Moon's surface. Estimate the work done by the pull of the Moon on the lunar lander as it approaches the lunar...
  37. S

    Why work done by a force is a scalar product

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  38. P

    Calculating Work for Permanent Magnet Fields

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  39. I

    Work Done in an Electric Field

    Suppose we have an electron in a uniform electric field by two parallel plates A and B. (Plate A is higher in potential than B), and we have an electron on plate B moving to A, am I right to say that the electron is losing its own EPE to convert it to KE and there is no work done by electric...
  40. P

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  41. gracy

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    Homework Statement Consider a point charge Q placed at point O.Consider any point p in the field of the Q.Charge q is placed at point p.Charge q is then moved from point p to s the distance i=between p and s is dr.Calculate work done. y Homework Equations ##dW=##-##F^→.dr^→## The Attempt at a...
  42. shanepitts

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  43. E

    Work done incline block system

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  44. J

    Work Done by Gas w/ Pressure & Volume Relationship

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  45. Titan97

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  46. gracy

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  47. Titan97

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  48. Titan97

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  49. Tony Stark

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  50. Mr Davis 97

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