Work done Definition and 1000 Threads

1. The problem statement, all variables and given/known A constant Force= <2,4,1> (in Newtons) moves an object in space from (0,0,0) to (2,4,5) ( distance is measured in meters) Calculate the Work done. 2. Homework Equations W= || proj of F onto pq|| ||PQ|| W= F• vector PQ 3. The Attempt...

Homework Statement Picture a rod of length L with N turns of wire around it What is the work done when one doubles the magnetization? We'll assume the coil has negligible resistance. Homework Equations \mathcal M is total magnetization of the rod. M is magnetic moment C_c is...

Homework Statement Basically I have the following problem. Given the equation of state \sigma = \frac{b}{T}\frac{L - L_0}{L_0} where b and L_0 are positive constants, calculate the work done over a Carnot cycle by a wire with this equation of state.Homework EquationsI already have the work...

Homework Statement An ideal gas at initial temperature T1 and pressure P1 is compressed by a piston to half its original volume. The temperature is varied so that the relation P=AV always holds and A is a constant. What is the work done n the gas in terms of n (moles of gas) R (gas constant)...

In First law of thermodynamics , work done by the gas is given by pΔV . I have few doubts regarding this- 1)Is 'p' ,pressure of the gas or external pressure of the surroundings ?If gas is expanding then surely gas pressure should be more than that of the surroundings and vica versa ...

Homework Statement Homework Equations The Attempt at a Solution I don't think the given problem requires me to find an expression of potential energy as a function of the equal side lengths. Also, I am not sure how would I set up the integral even if I want to find the expression...

There is a container containing water (state 1) which is being stirred. There is a temperature rise (state 2) due to stirring. It is required to find out change in entropy of the system if the process is reversible. Since, there is no heat transfer there would be no change in entropy due to...

Homework Statement a student lifts a book of 0.95 N to a height of 1.25 m. Then the student carries the book to a shelf at a distance of 8.0 m and places it at a height of 2.0 m. How much work did the student realize over the book? Homework Equations W = Fd The Attempt at a Solution...

Homework Statement A point charge q is moved inside a hollow charged cylinder of radius R. The initial point A is a distance (3/4)R from the center and the final point B is at the center of the sphere. How much work is done by the electric force in this case? 2. The attempt at a solution I...

Hi all, I was wondering if I am having a definition problem on mechanical work. Since dW = -PdV (as I was told in class), is it correct to say the pressure is fixed with W = -PV, since dW = d(PV) = -VdP - PdV = -PdV suggests dP = 0? Thanks S.

This is a purely conceptual question that I’m having trouble understanding. From what I understand, anytime an energy transfer takes place as work, you can say that something has done work on something else. For example, if the gas in a cylinder with a piston on it pushes back the atmosphere...

Today in an engineering thermodynamics lecture, the professor gave an example of a gas doing work. We had a cylinder full of helium at a pressure of something like 200kPa absolute and the valve was opened so that the gas would flow out against the atmospheric pressure until the pressures were...

Homework Statement In the thermodynamic cycle as shown, a) What is the direction that the cycle is executed-clockwise or anticlockwise? b) What is the work done? Homework Equations First law of thermodynamics for a cycle E2-E1= Q-W= Tds-Pdv=0 The Attempt at a Solution a) I...

Suppose a man is climbing up a hill at angle 30 degree from the ground. The mass of the man is 50Kg and he climbs up the hill at uniform acceleration of 2m/s2. What is the work done in climbing up the hill and if he climbs down the hill at the same 30 degree angle with uniform acceleration of...

The static friction force which provides the acceleration of a car does not move through a distance (the point of application is stationary with respect to the road at any instant). Isn't it that only external forces may change the translational kinetic energy of an object? If so, and if the...

Homework Statement This was a thermodynamics question; A fluid is being moved by a pump though a 1inch diameter tube. The density is 100 lb/ft3 with a flow of 12 lb/s. The pressure rises 40lbf/in. Assume there is no heat transfer. Find hp of the pump to the nearest 1/4hp. Homework...

Homework Statement A hot air balloon of mass 425 kg ascends from the ground level and accelerates at a rate of 1.25 m/s/s for 25 seconds. How much work is done by the upward buoyant force on the balloon? (conceptual) A certain amount of work W is required to accelerate a car from rest to a...

I have a small doubt regarding the workdone derivation in adiabatic process. Here is the derivation W= (P1V1-P2V2) = mR(T1-T2)/n-1 AS we know R/n-1 = Cv and Cp/Cv=1 also considering m=1 W=Cv(T1-T2) but in textbook it is quoted as...

As I understand it, pulleys will reduce the force needed to lift objects but require a greater distance. As the number of pulleys increase, the force decreases. But for all cases of pulleys, the work required to lift a given object to a given height will always remain the same. When I attach...

Using Knight's Physics : A Strategic Approach (3rd edition): I am on the section concerning dissipative forces. A box is pulled with a rope on a surface with friction at a constant speed. The book says Wtension=Change in thermal energy. By Newton's First Law, the book says: Change in thermal...

I am stuck with the above question, my answer to a is 40J but the model answer is 30J Really frustrating as the book I am ready only goes over straight line graphs

Homework Statement Using Stokes law, calculate the work done along a curve ##\Gamma ## which is defined as edge of a spherical triangle in first octant of a sphere ##x^2+y^2+z^2=R^2##. Vector field is ##\vec{F}=(z^2,x^2,y^2)##.Homework Equations Stokes law: ##\int _{\partial \Sigma...

Homework Statement A vector field ##\vec{F}(x,y,z)=(e^y+z^2cosx,xe^y,2zsinx)## is given and a curve ##\Gamma## with parametrization ##\vec{r(t)}=(sin(3t),cost(5+sin(10t)),sint(5+sin(10t)))##. Calculate the work done along the curve ##\Gamma## for ##t\in \left [ 0,2\pi \right ]##Homework...

A spiral spring exerts a restoring torque on an axis proportional to the angle through which the axis is turned. If it provides a torque of 10-5 Nmrad-1, find the energy required to turn it through 180degrees from its relaxed state? My solution was simple Work done = torque* the angle theta...

Homework Statement A particle moves only along the x-axis, and is subject to a force towards the origin of magnitude kx^3. if the particle moves from x1 to x2 how much work does this force do on it? (consider the case x1<x2) Homework Equations W=Fd The Attempt at a Solution...

Homework Statement 500 Cal are added to a gas inside a cylinder with a piston (containing one mole) by an external heating device. The volume of the gas doubles without any change in it's temperature of 300K. How much work is done on the piston? Homework Equations The Attempt at a...

Problem: Points A and B each have an electric potential of +9 V. How much work is required to take 2 mC of charge from A to B? Equation: V = W / q 9V = W / .002 C W= .018 J. This answer I'm getting is incorrect and I'm not sure what else to try. Any help in the right direction would...

Homework Statement Calculate the work done by a 52.98 kg person, who climbs a set of 0.20 m tall stairs (starting from rest) in 2.96s. Calculate the power required to achieve this. Homework Equations w=F•d The Attempt at a Solution My issue with this question has been identifying...

I learned that work done by gas is zero when a gas expands in vacuum. But the volume and pressure of the gas change.Then how work done by gas is zero?

Homework Statement 10kg is attached to the end of a string, which is thread through a vertical tube. The string and the tube always make a 90 degree angle. The distance from the tube to the mass is R and the velocity at which it rotates is V. How much work is done to shorten the distance...

Homework Statement a rope is used to pull a 3.57kg block at constant speed a distance 4.06m along a horizontal floor. the force on the block from the rope is 7.68 N and is directed 15 degrees above the horizontal. a) calculate the work done by the ropes force b) calculate the increase in...

Homework Statement Homework Equations Area of a triangle is 0.5 × b × h ΔW=VΔQ The Attempt at a Solution I drew a straight line graph from the origin with end point 4.5V 9.0 microF energy is a work done = .5QV There is a mark in the mark scheme for ΔW=VΔQ explained...

A parallel plate capacitor of circular cross section r>>d, and separation d. It is charged to potential V then disconnected from the circuit . What will be the work done in moving the capacitor from d to d1? Answer: Here the initial energy is 1/2CV^{2} Where C=Aε/d While moving the capacitor...

work done -- moving a charge in an electric field Homework Statement Q=10uC from origin to (3m,pi/4,pi/2) E=10r unit r + 5/(rsin(theta) unit phi V/m answer is -475uJ I found this problem in a reference book that gave answers, this problem is similar to a homework problem...

I know that I'm wrong but couldn't find where I'm Stress=internal force /area When the body is in equilibrium, force applied equals internal force.therefore stress=force applied/area Let us stretch a rod by two equal and opposite force.,say f and -f...thus total force is zero Stress=...

Homework Statement Evaluate the work done W = op∫ F\bulletdr By the two dimensional force F = (x2, 2xy) along the following paths from the origin to the point P(1,1): 1) This path goes along the x-axis to the point Q(1,0) and then directly up to the point P(1,1). 2) Along the path y...

Homework Statement Our teacher isn't very descriptive: A ring of radius "a" and resistance "R" is placed at the center of a long solenoid with "n" turns (assume the solenoid is longer and wider than the ring) with its axis lined up with that of the solenoid. Find the amount of work done to...

"A 1200kg car as kinetic energy 125kJ at the bottom of a 20 degree slope. It rises to a height of 10m. Calculate work done against friction." Relevant equations: Work = force x distance in direction of that force Work = KE = 1/2 x m x v^2 I'm not really sure where to start...tried...

Homework Statement A small motor is used to operate a lift that raises a load of bricks weighing 500N to a height of 10m in 40s at constant speed. The lift weighs 300N. What is the work done by the force of the motor? What is the work done by the force of gravity? Homework Equations P...

Homework Statement How much work did a horse do that pulled a 200-kg wagon 50 km without acceleration along a level road if the effective coefficient of friction was 0.060? Homework Equations W=Fnet * d Force of friction= µmg The Attempt at a Solution...

The problem as it appears on the problem sheet: A block of weight mg = 500 N is sitting on a horizontal floor. The coefficient of kinetic friction is \mu_{k} = 0.4. In class, we determined at what angle from the horizontal I should pull on the block if I'm weak and need to minimise the force F...

A trivial question. I know that current is the amount of charge passing per unit time across a area. And Potential difference is change in potential or change in potential energy per unit charge or work done per unit charge. And also from Ohms law, V is directly proportional to I. So...

Homework Statement An object is moving along some path. the total work done on the object during this process is zero. Homework Equations no equation The Attempt at a Solution A the speed of an object has decreased. B the speed of the object may have changed. C the object must be...

Homework Statement A single constant force F = (2.84i + 4.60j) N acts on a 4.12 kg particle. Calculate the work done by this force if the particle moves from the origin to the point having the vector position r = (1.52i - 2.55j) m. Homework Equations W=FD The Attempt at a...

Work done= force.displacement In space, with no external forces, air drag, gravity etc if you apply a force to object if will move forever in the direction of force unless any resultant force act on it to change its momentum. In this case let's take force as 2N so we get w.d=2N.s s will...

Problem: A father pushes horizontally on his daughter's sled to move it up a snowy incline, as illustrated in the figure, with h = 3.6m and θ = 15°. The total mass of the sled and the girl is 35 kg and the coefficient of kinetic friction between the sled runners and the snow is 0.20. If the...

My textbook says that if you are on a ferris wheel that is rotating, the total work done by all the forces acting on your is zero. How is that possible? You are moving so isn't work being done to you?

So I was thinking about the Universal Law of Gravitation, and the force of an object depends on the radial distance from Earth for simplicity. As an object travels to the center of the Earth the Fg increases as the radial distance decreases.F=(G*m*m*1)/(r^2). Knowing that the Force is not...

Homework Statement "You carry your 14.0 kg bag of textbooks horizontally 1.8 m above the ground, at constant velocity for a distance of 25 m. Ignore wind resistance. How much work do you do on the bag in the process?" Homework Equations W=Fd F=ma The Attempt at a Solution If work...

Homework Statement I can't figure this out...if you have a gas in a rigid container, with a membrane separating the gas from a vacuum in the other half of the container, then remove the membrane and allow the gas to expand, is any work done? It's not expanding against force - does that make...