Work done Definition and 1000 Threads

Homework Statement An object with a mass of 2kg gets accelerated from 15m/s to 25m/s. A: What is the work done in effecting this velocity change? B: The distance moved was 8m, what force produced the acceleration? C: How long did it take to produce the acceleration (presumed...

Homework Statement An ideal diatomic gas undergoes an adiabatic compression. Its initial pressure and volume are 1.20 atm and 0.200 m^3 and its final pressure is 2.40 atm. How much work is done by the gas?Homework Equations W = -\int p \cdot dVThe Attempt at a Solution So after integrating I...

i still don't really get how there is no work done on a book for example when am holding it and moving ?! i am a 9th grade student and when i ask this weird physics teacher of mine she keeps telling me that when i am holding the book it becomes a part of my body O__o i am not convinced at all...

Homework Statement We want to calculate the work done by kicking the soccer ball. The acceleration of the ball is 6m/s^2. The mass of the ball is 0,5 kg. The distance the ball travels is 20 meters. The distance that the foot kicks the ball is 10 cm. Homework Equations W=Fd F=ma The...

Homework Statement An object of mass m is moved straight up by a distance h. The work that gravity does on the object is: (a) -mh (b) +mh (c) -mgh (d) +mgh (e) None of the Above Homework Equations Work = ∫F dl PE = mgh The Attempt at a Solution I have a feeling the answer is (c)...

Homework Statement It takes 25 turns to drive a screw completely into a block of wood. Because the friction force between the wood and the screw is proportional to the contact area between the wood and the screw, the torque required for turning the screw increases linearly with the depth...

Homework Statement A 700 kg crate is on a rough surface inclined at 30°. A constant external force P = 5600 N is applied horizontally to the crate. The force pushes the crate a distance of 3.0 m up the incline, in a time interval of 7.3 s, and the velocity changes from v1 = 1.4 m/s to v2 = 2.5...

Homework Statement A constant external force P = 160 N (diagonally with an angle of 30) is applied to a 20-kg box, which is on a rough horizontal surface. The force pushes the box a distance of 8.0 m, in a time interval of 4.0 s, and the speed changes from V1 = 0.5 m/s to V2 = 2.6 m/s. The work...

im having a hard time to solve this work done by overcoming friction question. help please? Question: a block with mass 30kg slide on a rough inclined plane with 8m long and 28 degree to horizontal with acceleration 1.5ms^-2. a)Calculate the work done to overcome friction. b)the coefficient of...

Please see attached images. Those pencil-written answers are directly copied from marking scheme (after using considerable amount of time calculating and still getting the wrong answer) 1. For question 1, why is the weight taken as 3.8N regardless of the additional force F? 2. In...

Hi there everyone, Would like some checking of my work or comments. Would like the work done on a falling mass M as a function of time. To begin, the relation for work as function of distance.. w = Mgx but would like as function of time so substitute x this way, x = (1/2)gt2...

In our formulation of work done by a Force we say it is ∫ F.dl ... My knowledge of integration means adding Infinitesimal parts. We write dl because it is the smallest part of the distance moved. My question is why have we written F and not dF... Thanks for clarifying!

Homework Statement http://postimage.org/image/gprwhko37/ Could someone check my work to make sure I'm doing this problem correctly? Where: s : hypotenuse or distance h : height uk : coef friction Homework Equations W = F*D Force Normal = mgcosθ Wfriction = (uk * N) *...

Homework Statement Find the work done by a force acting in the direction 2i - 5j + k in moving a particle from (3, 3, 1) to (1, 2, 4). Homework Equations The Attempt at a Solution I just found the displacement vector (2,1,-3) and did the dot product with the force vector...

Hello physics whizzes. How much force is required to raise an item weighing 5,000kg to a height of 50 meters in a frictionless environment? It seems that all you would do is F = MA = (5000) (9.80665) = 49,033.25 Newtons, and that the height is irrelevant assuming that the gravity stays...

a strong steady wind provides a force of 170 N in a direction 30 degrees east of north on a person. If the person walks first 110 m north and then 190 m east what is the total work done by the wind? I used W=FDcosθ 170(110)cos(30)=16194.67J 170(190)cos(30)=27972.62 should 110 m north be...

A box of mass 5.0-kg is accelerated from rest across a floor at a rate of 2.0m/s^2 for 7.0s. Find the net work done on the box? W=Fd

You slide a box of books at constant speed up a 30^\circ ramp, applying a force of 210N directed up the slope. The coefficient of sliding friction is 0.18. 1. How much work have you done when the box has risen 2m vertically? 2.What is the mass of the box? I think I could solve...

Homework Statement A chain of mass 4Kg and length 2m is lying on a table, such that 60 cm of one end is hanging from one edge off the table. Find the work done to pull the entire chain on the table. Homework Equations (anything that'll work i suppose) The Attempt at a Solution I...

A worker pushed a 23 kg block 13 m along a level floor at constant speed with a force directed 22° below the horizontal. If the coefficient of kinetic friction between block and floor was 0.40, what were (a) the work done by the worker's force and (b) the increase in thermal energy of the...

Say we have a friction-less inclined plane in the shape of a right triangle, sloping downward to the right. The angle above the horizontal axis is inconsequential for these specific purposes aside from the fact that we know it is inclined above said axis. We then have a block sliding down (to...

Homework Statement What is the work done in moving a 0.2 µC point charge from corner a to b of a square abcd, when a 10 µC charge exists at the center of the square? Homework Equations Work or ΔU=q*V V=kq/r The Attempt at a Solution V=kq/r V=(9.0x10^9)(0.2x10^-6)/r This is...

Homework Statement Here is the solution from the textbook: I don't understand how they can assume a linear relationship. In fact I don't even understand the math... Why does the solution take the average pressure? Isn't the relationship between pressure and volume PV^n = constant?

A helicopter lifts a 90 kg astronaut 13 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/12. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her? Just before she reaches the helicopter, what are...

How would one prove W = F.s and why would only F.s be conserved (in energy conservation) and why not F.s^2, or F.s^3? One possibility is by experimental observation and verification. But how would one go about it without experimentation? s = Displacement vector F = Force vector and by dot...

I have a gas container which contains gas at high pressure. The gas container is fitted with a capillary tube which opens into the atmosphere. Now we have a stopcock fitted to the capillary tube. We opens the stop cock slightly and allows the gas to leak outside. The process will go on till the...

Homework Statement Find the work done by an ideal gas on a hooke's spring when heat is added until volume and pressure triple Homework Equations Pv=nrT Q=ncΔt W=(1/2)kx^2 F=kx=P*A The Attempt at a Solution I took the work equation for the spring and subbed in P*A to get w=(1/2)(PA)Δx and...

A block is attached to a spring which is attached to a stationary wall. When the block is pulled out to x = +5.0 cm, we must apply a force of magnitude 370 N to hold it there. We pull the block to x = 14.0 cm and then release it. How much work does the spring do on the block when the block moves...

The facing surfaces of two large parallel conducting plates separated by 10.0 cm have uniform surface charge densities that are equal in magnitude but opposite in sign. The difference in potential between the plates is 500 V. An electron is released from rest next to the negatively charged...

Say you have an object on a smooth friction-less slope, and a force 10N (acting parallel to the slope) is applied to it to move it at a distance 5m up the slope. Work done by the force is: force*distance. In this case, 10*5 = 50 joules of energy Does all that energy get transferred to...

\Homework Statement Air is compressed in a piston-cylinder assembly from p1 = 10 lbf/in2, T1 = 500°R to a final volume of V2 = 1ft3 in a process described by pv1.25 = constant. The mass of air is 0.5 lb. Assuming ideal gas behavior and neglecting kinetic and potential energy effects, determine...

Homework Statement Consider a frictionless piston inside a cylinder, both with a cross sectional area A. 1) By considering the work done by the gas on the piston and the work dW required to move the piston a distance dx, show that the work done by the gas is dW = -pdV. 2) 1 L of an ideal...

Homework Statement Derive an expression for the amount of work done when one mole of an ideal gas expands isothermally at a temperature T from an initial volume V1 to a final volume V2. Homework Equations PV = nRT W = V2∫V1Pdv The Attempt at a Solution I'm not really sure how to go...

Homework Statement http://imgur.com/BWo3tLh Using the fact that the weight of water is 62.5lb/ft3, find the work (in ft-lbs) required to pump the water out of the outlet when r =3ft. Make sure your answer is correct to within ten ft-lbs. Homework Equations The Attempt at a...

Homework Statement A positive point charge (q = +8.9 10-8 C) is surrounded by an equipotential surface A, which has a radius of rA = 1.3 m. A positive test charge (q0 = +2.7 10-11 C) moves from surface A to another equipotential surface B, which has a radius rB. The work done by the electric...

Homework Statement Three charges, q1, q2, and q3, are located at the corners of an equilateral triangle with side length of 1.49 m. Find the work done in each of the following cases: a) to bring the first particle, q1 = 1.33 pC, to P from infinity b) to bring the second particle, q2 = 2.99...

I want to show that the work done by compressing a container of gas with uniform pressure is -\int_{V_i}^{V_F} p(V)dV, where p(V) is the pressure of the gas as a function of volume. This equation was derived in my text for the special case of a piston, but I wanted a more general derivation...

Homework Statement I am looking for some clarity on what should be general conceptual questions involving work, net work, and work done by friction. In General; W[F]=the component of the applied force acting in the direction of motion X distance OR Δenergy W[friction]=μN and is...

Suppose you have many forces acting on an object, and the object moves in space in some time interval. Each force has done some work on the object. Suppose you took all these values for work, added them up, (they are all scalars). You'd obtain a scalar equal to the net work done on the object...

I have always managed to solve problem asking how much work is being done but then once I start to think about the work being done I get confused. E.g A barrel of weight 200N is raised by a vertical distance of 1.8m by being moved along a ramp. The work done here would be 200 x 1.8 =360J . I do...

Homework Statement A force acts on a particle and is given by the following expression: F(x,y)=2x^3 y^2 i+3xy^3 j What is the work done by this force in moving the particle from a position (x,y) = (0,0) to (4,2) along the path given by the curve y=√x ? Homework Equations I know...

Homework Statement "a metal wire of diameter .23mm and unstretched length 1.405 is suspended vertically from a fixed point. when a 40n weight was suspended from the lower end of the wire, the wire stretched by an extension of 10.5mm. calculate the work done on the spring."i know the formula for...

Homework Statement A particle with a charge of 3.2x10^-19 C accelerates from rest between two charged plates. The electric field is uniform and is 39000 N/C. The distance between the plates is 4.5x10^-3 m. A) Calculate the force on the particle B) How much work is done by the electric...

Homework Statement I'm reading Feynman's lectures on physics to brush up on material I haven't looked at in a while, and I got confused by one of his statements. He claims that the change in potential energy of an object traveling down a slope can be calculated solely by the change in...

Homework Statement Ram and Shyam both climb a hill. They have the same mass. Ram wins the race and reaches in 5 Minutes but shyam reaches in 7 mins.Choose the correct Statement: A)Ram and shyam do the same work but exert different power B)Ram and shyam do different work and exert...

Hey guys, can the work done on a body be described as the function of time during which a force acts upon it?

Hello 1- work done to push body forward is greater than to pull body backward what is the explanation for this?can you draw the two FBD in both cases ? 2- why is nail driven in wooden wall but not in the concrete wall ؟ I guess this is somehow related to Newton's third law Thanks

Okay, the problem is: A 1200~kg satellite is in a circular orbit around the Earth at a radius of 8.77\cdot 10^6~m. What is the work done by gravity when the satellite has gone a quarter of the war around its orbit? The acceleration due to gravity at the height of the satellite is 5.19\cdot...

Homework Statement compute the work done by the force field F(xyz)=[(yze^(xyz)+y^2+1)i+(xze^(xyz)+2xy)j+(xye^(xyz))k], in moving the object along the path C from beginning to end. here C is the path paramterized by r(t)=<t, (t^2)-1, t+2>, 0<_t<_1. The Attempt at a Solution Would i be...

An 8000kg aluminum flagpole 100m long is heated by the sun from a temperature of 10°C to 20°C. Find the work done (in J) by the aluminum if the linear expansion coefficient is 24*10-6 /°C. (The density of aluminum is 2.7*103 kg/m3 and 1 atm = 1.0*105 N/m2) I know w=PΔV, and I know V at 10°C =...