Work done Definition and 1000 Threads

Homework Statement The question is as following: http://i56.tinypic.com/se547s.png Homework Equations W = F x distance or p d(v) . Potential energy : mgh , k.e : 1/2mv^2 The Attempt at a Solution Well I am stuck on part c, now I am aware that in adiabatic process Internal...

Homework Statement The question is as following: One litre of an ideal gas, initially at atmospheric pressure, is held at a constant temperature of 300 K (by maintaining good thermal contact with a thermal reservoir held at this temperature). The volume is decreased until the pressure doubles...

Homework Statement A spring has a relaxed length of 5 cm and a stiffness of 95 N/m. How much work must you do to change its length from 2 cm to 10 cm? k=95 Lnull=0.05 delta x = .1-.02 = 0.08 Homework Equations F=-kx W=Fdcostheta The Attempt at a Solution I honestly have...

Why is the change in potential energy the NEGATIVE of the work done by a force? What is the negative sign doing there, and what physical meaning does it serve? Any input is appreciated, but a rather detailed explanation would be great, as I am having much difficulty understanding this.

Homework Statement System is initially at rest, if m2 falls a distance h. What is the work done by gravity on the system. Given: Theta, m1, m2, h The image looks fairly similar to this. Homework Equations I'm going to go ahead and assume we are using Work(gravity)=The change in...

i don't understand how to find the "work" done A driver of a 7475 N car passes a sign stating "Bridge Out 25 Meters Ahead." She slams on the brakes, coming to a stop in 10 s. How much work must be done by the brakes on the car if it is to stop just in time? Neglect the weight of the driver, and...

A flight attendant pulls her 70.0 N flight bag a distance of 269 m along a level airport floor at a constant speed. The force she exerts is 32.0 N at an angle of 52.0° above the horizontal. (a) Find the work she does on the flight bag. _5299_J (b) Find the work done by the force...

Homework Statement I have a brick of mass m in my hand. I move the brick vertically up h meters. Homework Equations What is the Work done to the brick by gravity? The Attempt at a Solution Work = Fd The F for my hand on the brick is mg going up and d is h so the work done by my...

Homework Statement On my formula sheet I have this: W=(C/1-y)(Vf^(1-y)-Vi^(1-y)) y=Cp/Cv Homework Equations The Attempt at a Solution I am confused about what the C in C/1-y stands for. My textbook does not even have this formula and I realized that C is not Cp or Cv...

Homework Statement A gas is trapped in a cylinder-piston arrangement. The initial pressure and volume are 13,789.5 Pa and 0.02832 m^3. Determine the work(kj) assuming that the volume is increased to 0.08496 m^3 in a polytropic process with n=1. Homework Equations m_1-2=∫PdV from 1 to...

Homework Statement The torsion spring at A applies the counterclockwise couple C(θ)= − 10θ N · m to the uniform bar.The angle θ (in radians) is measured counterclockwise from position 1, where the spring is undeformed. Calculate the work done by the spring on the bar as it rotates from...

Homework Statement Jennifer lifts a 2.5 kg carton of cat litter from the floor to a height of 0.75 m. (a) How much total work is done on the carton during this operation? Homework Equations Work=PE=mg.y The Attempt at a Solution Work = 2.5kg*9.8m/s^2*0.57m= 18.4J However the...

ques: how fast block moves after sliding 100 cm on incline?[by energy conservation] A frictional force of 0.5 n actsdoubt: should work done by tension be accounted?

So I was sitting on the train last weekend, reading through my physics book on mechanical work and its relation to kinetic energy. One example would be that a box on a frictionless table being pushed and they would conclude that W = ΔK = ½mΔv2. Looking at this equation got me thinking...

Homework Statement One mole of a monatomic ideal gas is taken through a reversible process from an initial state "a" to a final state "b" during which the pressure of the gas varies with volume V as shown below. Calculate the work Won[/on](a->b) done on the gas during this process...

1. Statement of the Problem One mole of a monatomic ideal gas is taken through the reversible cycle shown. Process bc is an adiabatic expansion, with P_b = 10.0 atm and V_b = 1.00E-3 m^3. Find a) the energy added to the gas as heat, b) the energy leaving the gas as heat, c) the net work done by...

Homework Statement A block of mass M=3.4 kg is dragged over a horizontal surface by a force F=20.0 N. The block is displaced a distance d=17.0 m, the friction force Ff is 3.3 N. What is the work done by the friction force? Homework Equations Ff=μkFn The Attempt at a Solution I...

In my thermodynamics class, we were shown an equation that gives the work done by expanding pressurized gas given as the integral from v1 to v2 of C/V*dV where C is a constant and v1 and v2 are initial and final volumes respectively. My question has to do with the fact that this is basically...

The "work" done by two electromagnets It has been said that magnets attract and repel by involving the use of electric fields. If so, how does the shape of the electric field change when an iron bar is magnetized? I would presume that the relative motion of the magnet as a whole is not what...

Homework Statement calculate work done to compress 1mole of ideal gas from 1atm to 0.5atm at 298K where it is subjected to constant external pressure of 1atm Homework Equations Won = -Integral pdV = -(1atm)(Vf-Vi) = -p(RT/pf - RT/pi) = 2270J where i have assumed T does not change, is...

Homework Statement How much work is required to assemble eight identical point charges, each of magnitude q, at the corners of a cube of side s? Note: Assume a reference level of potential V = 0 at r = infinity. (Use k_e for ke and q and s as necessary.) Homework Equations V = E.s U = q.V V =...

the work done to move 4 C of change from a point to another point in an electrical field is 100J.What is the potential difference between the two points?

Homework Statement 1.Calculate the work done by the force F=i cos(pix/4) + j y2 along the path y=x2 in the x-y plane from (0,0) to (2,4). 2.Is the force F conservative? Explain. Homework Equations Work = Integration between a and b of F.dl The Attempt at a Solution 1. I know...

Homework Statement Calculate the work done on the crate during the journey Homework Equations WD=F*S The Attempt at a Solution I know its simple but I am just double checking more than anything, the force pulling the crate is 482.96N and the distance is 20M. Now i would...

A boy catches a ball of mass 150g, which is moving at 20ms^-1 A) calculate the force which he must exert to stop it in (i) 0.10s (ii)0.50s Im resonably sure i use the formula W=F.D what confuses me is that to find the force i have to use F=M.A but 20ms^-1 is not accelleration. if not...

Homework Statement X & Y are two points at respective distances R and 2R from the centre of the Earth, where R is greater than the radius of the Earth. The gravitational potential at X is -800kJkg^-1. When a 1kg mass is taken from X to Y, what is the work done on the mass?Homework Equations...

My Question - Steam at 200 psi and 600 F flows through a turbine operating adiabatically and exits at atmospheric pressure. For every kilogram of steam flowing through the turbine there are 150 Btu of shaft work delivered. (a) What is the final condition of the exit steam? (b) What is the...

For example: i) Someone lifts 2kg flowerpot 1m vertically upward. The work done by the gravity is -19.62 J? Then, if ii) A 3kg box on the floor is lifted vertically up onto the head and then lowered down to the shoulder. The shoulder is 150cm while the top of the head is 175cm measured...

I have studied in my lower grades that work(w) done or energy is the product of force(f) and displacement(s).Till now I was thinking that this was true. I was not taught that it was the dot product of force and displacement. according to this definition, the work done when the force and...

If the total work done is calculated using the area of the closed curve (Force vs Displacement), then the formulation doesn’t care if the force is conservative or not. Is that right? For instance, if I understand it right, spring force is a conservative force and hence work done by the spring...

I have been scratching my head on this problem and hope that someone might solve my problem. The question is about work done by a variable force on a spring. When a spring is stretched x distance from its initial position by an external force.Why the work done by the external force is not equal...

A child on a sled (having a combined mass of 47.0 kg) is pulled by a force directed along a rope that makes a 45 degree angle with the horizontal axis. the force exerted on the rope is 100.00 N. the force of friction acting on the sled is 30.0 N. if the child is pulled a distance of 10.0 m along...

Homework Statement Calculate the work done by the system in an irreversible (single step) adiabatic expansion of 2 moles of a polyatomic gas (\gamma = 4/3) from 300K and pressure 10 atm to 1 atm. Homework Equations Work done in adiabatic process W = nCv\DeltaT...

Homework Statement What is the work done to place a satellite of mass 600kg which orbits the Earth at a radius of 8.00 x 10^6 m. The Attempt at a Solution 1st attempt : W= F x d = GmM/(r^2) x r = GmM/r where r is the radius of the satellite The answer I got is 3 x 10^10 J which is...

I'm reviewing a concept on a system where a mass is hanging from a vertical spring in the presence of gravity. I'm attempting to validate my understanding of conservation of energy when the mass is allowed to slowly extend from its unstretched point to its equilibrium point where the forces...

PV = nRT When a gas in a cylinder expands, the gas pushes the piston upward against a constant opposing external atmospheric pressure P. The work done by the gas on the surroundings is w= -P\DeltaV \DeltaV is the change in volume My question is: Assuming the Temperature stays constant...

Homework Statement The question asks about an electron moving with energy K1, then says a force acts on the particle so that its velocity is 1/4th of what it was originally, but in the opposite direction. Find the amount of work done on the particle. b) Then, decide if the direction of the...

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...

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...

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...

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...

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...

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

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...

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...

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...

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...

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...

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...

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...