Work done Definition and 1000 Threads

Homework Statement A quantum particle of mass ##m## is bound in the ground state of the one-dimensional parabolic potential well ##\frac{K_0x^2}{2}## until time ##t=0##. Between time moments of ##t=0## and ##t=T## the stiffness of the spring is ramped-up as ##K(t) = K_0...

Just want to check that I've used the correct method for this thermodynamics question I've been set. Any clarification would be greatly appreciated. So I have a closed system in which a gas is compressed from a pressure of 3 bar absolute to 5 bar absolute. The volume changes from 0.9m^3 to...

Problem statement, work done, and relevant equations: One mole of ideal gas is initially at 1 atm and has a volume of 5L. a) Calculate the work done on the gas during an isothermal, reversible compression to a volume of 2L. ##W_isothermal = - \int_{v_i}^{v_f} p dv = - \int_{v_I}^{v_f}...

This is a concept that has long since plagued me. I will quote an article off of Google about the concept I am confused about: "Consider a collection of static point charges located at position vectors (where runs from 1 to ). What is the electrostatic energy stored in such a collection...

Homework Statement A cutting tool under microprocessor control has several forces acting on it. One force is F⃗ =−αxy2j^, a force in the negative y-direction whose magnitude depends on the position of the tool. The constant is α = 2.70N/m3 . Consider the displacement of the tool from the...

Homework Statement The net work done on a certain gas is 55J, and the net heat flow into the gas is -23J. What is the net work done by the gas? Homework Equations U = q + w The Attempt at a Solution This problem seems very conceptual so I didn't use the formula above. I just deduced from...

Homework Statement In a cylinder of an automobile engine, immediately after combustion the gas is confined to a volume of 50.0 cm3 and has an initial pressure of 3.00x106 Pa. The piston moves outward to a final volume of 300 cm3, and the gas expands without energy transfer by heat. (a) What...

Homework Statement Ok, so I've read many of the threads on here and they all say the same thing. I think I understand the Gauss Law and the theory behind the spherical shell. The question is this: Find the WORK done bringing a test charge q from infinity to the center of a spherical shell of...

Homework Statement Hey! Problem: A ball falls 8,5 meters, and hits the ground with 11 m/s. The ball has a mass of 0,2 kilos. How much work was done by Air resistance on the ball? Homework Equations I guess mechanical energy eqution? The Attempt at a Solution answer should be -4,5 joule...

In numerical of calculation of work done by/on the system (cylinder piston ) the formula used Work=± p(external pressure)multiplied by change in volume I want to ask should temperature be constant to apply this formula?I mean is this formula applicable only in isothermal condition?

Homework Statement A ball of mass m is attached to a string of length L. It is being swung in a vertical circle with enough speed so that the string remains taut throughout the ball's motion.(Figure 1) Assume that the ball travels freely in this vertical circle with negligible loss of total...

We want to slide a 12-kg crate up a 2.5-m-long ramp inclined at . A worker, ignoring friction, calculates that he can do this by giving it an initial speed of 5 m/s at the bottom and letting it go. But friction is not negligible; the crate slides only 1.6m up the ramp, stops, and slides back...

Let me answer this by not actually answering your question. I have an issue that bugs me, that is connected with it... Suppose I lift a box. Let us consider that the box is rigid, totally. I lift the box. I am separating it from the earth. When one separates attracting bodies, the one can...

In my textbook it says that work done by a nonconservative force (an applied force) has the same sign as the change of potential energy? For instance, if I push a positive test charge from an infinite distance away to a negative charge, then the test charge goes from high potential energy to...

I am having trouble calculating the work done by a product gas in reversible adiabatic expansion, and in calculating the final temperature. pV gamma = constant, Cv = constant (assume), gamma = cv + nR / Cv. anyone who can help me out?

Homework Statement A crane lifts a 1250 kg load directly upward with a constant speed through a vertical distance of 8 m. How much work is done by the tension in the crane cable? Homework Equations Im thinking its the work equation but this is were i got stuck W = m(as)The Attempt at a...

Homework Statement Hi, I am trying to work out the energy needed to move a certain quantity of (ideal) gas using a fan but am finding a great discrepancy between my calculations and those supplied by the fan manufacturers. let's say i'd like to move 1kg of air (1kg/m3) a distance of 1m. I get...

Dear All, would really appreciate some help with the following question - am struggling with dynamics at the minute! 1. Homework Statement An 8kg mass is suspended from a grooved drum at radius r1=200mm and with a speed of 0.3m/s it drops 1.5m. The outer radius of the drum is r2=300mm. Assume...

Homework Statement A force ##F=4x## is applied on an object. What is work done to move it from ##x_1=2m## to ##x_2=4m##? A)12 J B)24 J C)32 J D)48 J Homework EquationsThe Attempt at a Solution The displacement, ##x=4-2=2m## Force, ##F=4x=4 \times 2=8N## Work ##W=\vec F \cdot \vec x=8 \times 2...

Homework Statement A manned expedition is planned to be sent to Mars in 2023, one way. If the colony module was 100.0 tonnes in mass. Determine the work that must be done by the rockets to carry this colony from Earth to the surface of Mars. Homework Equations ET = PE +KE PE = -GmM/r KE =...

Something I have read in Griffith's Electrodynamics is confusing me. In deriving the Poynting vector, he says to suppose that we have some charge and a current configuration which at some time t produces fields E and B. In the next instant, dt, the charges move around. He then asks the question...

I feel like I'm missing some obvious or simple piece but I can't seem to figure out the first part. If I can get the first part, the second part is easy. 1. Homework Statement An 80-kg baseball player running at 6.5 m/s goes into a slide 3.0 m from second base. He comes to rest just as he...

Homework Statement [/B] A tennis player strikes an incoming tennis ball of mass m and speed v such that the ball leaves the racket at speed v as well. How much work was done by the tennis player to reverse the direction of the ball? Explain. Did the tennis player do any negative work? Homework...

Homework Statement A quantity of ideal gas (0.800mole) at a pressure of 10.0atm and 200K is allowed to expand isothermally until it reaches a pressure of 1.00atm. Calculate the work done if this expansion is carried out a) against a vacuum, b) against a constant external pressure of 1.0atm and...

1. A body, whose mass is 10kg, is vertically raised upwards h=2 m . 230J work was done. Find the acceleration.Homework Equations W = Fh F = ma The Attempt at a Solution W = Fh F = A/h = 230J / 2m = 115J F = ma a = F/m = 115J/10kg = 11.5 m/s^2

Homework Statement Decomposition of 2 moles of NH4NO3 at 100 degrees C.calculate work done Homework Equations NH4NO3 (s)→N2O(g)+2H2O (g) work done= - RT delta n here R=universal gas constant T=temperature in kelvin and delta n=difference in number of moles of products and reactants. The...

Homework Statement A heat engine containing an ideal gas has a reversible cycle which consists of 2 constant volume segments with V = 1ℓ and V = 3ℓ and two constant pressure segments with P = 1 atm and P = 2 atm (see figure below). The temperature at point “c” is Tc = 273 K. A) Is the path...

I'm using a review book to study for physics but I don't understand how this answer was obtained. I got a different answer. When I googled the exact same question, I found a website that got the same answer as me... so is the book wrong? The question is as follows: 1. Homework Statement A 15...

So friction as a nonconservative force, is path dependent when it comes to how much work is lost from a system right? What confuses me however is understanding what that means, in terms of energy. So the work done by friction includes the energy that was neeeded to stop an obect (like a braking...

Hi all, I could use some assistance with the following problem. "The spring of a spring balance is 5.0in. long when there is no weight on the balance, and it is 9.6in. long with 8.0 lb hung from the balance. How much work is done stretching it from 5.0in to 12.2in?" So far, I know to take...

Homework Statement an escalator is moving downwards with uniform speed u and a man of mass m is running upwards on it with uniform speed v. if height of escalator is h find the work done by man in going up the escalator Homework EquationsThe Attempt at a Solution on my first shot at this...

Homework Statement I am trying to solve a spring mass system (mass m and constant spring stiffness k) where instead of applied force a displacement is applied as u=sin(ωt) where ω is the frequency and t is the time. I need to find the difference of the total work done and the energy (KE and PE)...

What is the difference between work done on an object and work done by you? For example, you exert a 100N force pushing a 10kg mass 3.0m across the floor with a coefficient of friction 0.60 1) what is the work done on the mass? 2) what is the work done by you? For question 1 I think it has to...

Hi, I'm trying to formulate some general ideas on how systems convert energy imparted by external forces. Could anyone please read the following and see if any of the statements and examples are correct? I really like the idea of thinking of isolated systems as "machines" through which energy...

A 1.2 kg block is held against a spring of force constant 1.0 x 10^4 N/m, compressing it a distance of 0.15m. How fast is the block moving after it is released and the spring pushes it away?

Homework Statement There is a block of weight mg sitting on a horizontal table with a coefficient of kinetic friction u, at what angle to the horizontal should one direct a driving force to minimise work done in moving the block a horizontal distance of 10m with nonzero velocity and what is the...

Hello, I am confused about a problem regarding work done and pulleys. I am confused mainly by the last two, but not 100% confident in the first two either. 1. Homework Statement Two blocks are connected by a very light string passing over a massless and frictionless pulley (Figure 2). The...

Homework Statement a ideal monoatomic gas initally has a temperature of 315K and a pressure of 6.87atm . It then expands from a volume of 440cm^3 to volume 1550cm^3 . If the expansion is isothermal, what is (A) the final pressure (in atm's) and (B) the work done by he gas. Homework Equations...

In my maths textbook, it says that work done can be defined as Force x Distance moved in direction of force, AND change in kinetic energy. I feel both these definitions can be contradictory Example: A box moves at a constant velocity along a rough horizontal plane. It has a driving force of 5N...

Homework Statement A vertical spring is 10.0 cm long when supporting a 20.0 kg mass, and it is 12.0 cm long when supporting a 32.0 kg mass. Assume the stretch is linear with the load. a) What is the length of the spring with zero load? (0.06666667) b) How much work would be done in...

Homework Statement A force exerts an impulse J on a particle changing its speed from u to 2u. The applied force and the initial velocity are oppositely directed along the same line. The work done by the force is-- Ans: Ju/2 Homework Equations Impulse= force*time impulse=change in momentumThe...

Work done = force applied * displacement So if I exert N1 force on a mass placed over a friction less floor, then the displacement = ∞. Then won't the work done = ∞. How is possible?

In experiment 1, two blocks of identical mass are pushed together with a force of magnitude F over a time interval deltaT. In experiment 2, the same force is applied to the same blocks over the same time, except there is a spring (initially at equilibrium) between the blocks. Is the NET EXTERNAL...

Homework Statement A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. What is the minimum amount of work that the worker did in lifting the...

Homework Statement A 310-kg feraligatr slides 3.0m down a 30∘incline at Rainbow Valley and is kept from accelerating by his trainer who is pushing on the feraligatr's back parallel to the incline. Express all your answers using two significant figures. a Howw much force does the trainer...

Homework Statement A person pulls a box (m=10 kg) horizontally with +2m/s2 acceleration by applying 45 N force. The displacement of the box is 8 meters from initial position. a) How much work is done by applied force? b) How much work is done by kinetic frictional force? Homework Equations Wf...

Homework Statement In the figure below (image attached) a constant force of 82N is applied to a 3kg box at an angle of 53 degrees causing the box to move up a frictionless ramp. How much is work is done by that force (Fa) when the box has moved through a vertical distance of .15m? Homework...

Apologies in advance if this question seems trivial, I seem to have missed something conceptually and would like some clarification. If an electric field from a point charge does work on another charge and thereby loses energy, where does the lost energy come from? It is my understanding that...

Homework Statement I'm working my way through MIT 8.02x, the intro E&M course, on EdX. In Homework 3/Problem 3, we insert a dielectric between plates in a capacitor that is connected to a battery supplying potential V. So the charge on the capacitor increases by Q. How much work is done by...

I would like the determine the work done by gravity on a mass attached to a rod (see the attached image). The rod is assumed to be weightless and rigid. I start from the definition of work: W_{AB} = \int_{\mathbf{r}_A}^{\mathbf{r}_B} \mathbf{G}\cdot \mathrm{d}\,\mathbf{r}. In the x-y coordinate...