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System Work

Work is performed by a system if the energy transferred by the system to another accounts for the change in external generalized mechanical constraints on the system. Thermodynamic work is a generalized concept of mechanical work in physics. Thermodynamic work is defined to be measurable solely from knowledge of such external macroscopic constraint variables. These variables always occur in conjugate pairs, for example pressure and volume, magnetic flux density and magnetization.

The SI unit for work is a joule (J). The rate at which work is performed is defined as power.

In thermodynamics, the quantity of work done by a closed system on its surroundings is defined by factors confined to the interface of the surroundings with the system and to the surroundings of the system. According to the first law of thermodynamics for a closed system, any net increase in the internal energy U must be fully accounted for. This can be seen in the equation below:

dU= δQ- δW


Apply a force ---> Displace an Object ---> Do work

Simulation Investigating Isobaric, Isochoric, & Isothermal Processes

Perform a simulation investigating three special processes - isobaric (constant pressure), isochoric (constant volume), and isothermal (constant temperature) - that can be derived from the ideal gas law. The simulation is found at Background Info 1. The simulation allows you to vary the pressure for an isobaric process, the vo

resonance in longitudinal waves and wave problem

The bottle is acting as a Helmholtz resonator. This is the same phenomenon that acts when you blow across the top of the bottle. The volume of the air inside the bottle and the mass of air in the neck of the bottle work together to determine the pitch of the resulting sound. As the bottle fills, the volume of air decreases, and

A problem on Atwood machine

An Atwood machine consists of masses of 1.5 kg and 1.66 kg on opposite sides of a light frictionless pulley. The system is given an initial velocity of 1.15 m/s in the direction of the 1.5 kg mass. * How much work does gravity do on the system between the initial instant and the instant at which the system comes to rest, and

Examining a Pulley Sytem

Please help with the following problem. Provide step by step calculations. An Atwood machine consists of masses of 1.9 Kg and 1.995 Kg hanging from opposite sides of a pulley. As the system accelerates 3.3 meters from rest, how much work is done by gravity on the system? Assuming no friction or other dissipative forces

Physics: Example Problem and Solution

A charged proton particle is moving rightward between two parallel charged plates separated by distance d= 6.60mm. The plate potentials are V1= -67.0 v and V2= -48.0v. The particle is slowing from an initial speed of 97.0 km/s at the left plate. What is its speed just as it reaches plate 2? A thin spherical, conducting shell

Physics: Magnitude of Gravitational Force

At a certain instant, the earth, the moon, and a stationary 1470 kg spacecraft lie at the vertices of an equilateral triangle whose sides are 3.84 x 10^5 km in length. a) Find the magnitude of the net gravitational force exerted on the spacecraft by the earth and moon. Find in N. b) Find the direction of the net gravitati

Infinitely long hollow conducting tube

Consider n infinitely long hollow conducting tube tht is split in half with each half held at the indicated potential. calculate B_o, B_n, A_n what equation would plot V(rho, pi/2). do not need mathcad work. attatched copy of diagram.

Compression of water

Please see attachment for full problem statement. By applying a pressure of 200 atm, you can compress water to 99% of its usual volume. Sketch this process on a PV diagram, and estimate the work required to compress a liter of water by this amount. Does the result surprise you?

Thermodynamics : Joule Cycle

(Please see the attached file) A Joule cycle consists of two adiabats and two isobars: 1--> 2 and 3 ---> 4 are adiabatic compression and expansion respectively; 2 ---> 3 and 4 ---> 1 are constant pressure expansion and compression respectively. Treat the working medium as an ideal gas with constant gamma = Cp/Cv. Note that a

Constant Velocity - Friction and Work

A 50 kg crate slides down a 6 m ramp inclined at an angle of 35 degrees to the horizontal. A worker pushes on the crate parallel to the ramp so that it slides down with a constant velocity. If the coefficient of kinetic friction is .33 a) Write equations of motion for the system b) Solve for the force exerted by the worker

System of Electric Charges

Please see the attached file. 3) A particle carrying charge qA = -8 × 10^-4 C is placed at point A and a particle carrying charge qB = -2 × 10^-4 C is placed at point B. a) Find the magnitude and direction of the electric field at point C. b) Find the electric potential at point C. c) Find the direction and magnitude

Light Rays and Optics

Solve the following problems in the space provided. Show your work. Write equations in symbolic form before making numerical substitutions, and include the correct units with any numerical result. 1. Light of 520 nm wavelength is used in a double-slit (Young's) experiment (slit separation 0.45 m). Adjacent dark fringes separa

Friction force acting on a block.

I have attached a picture file and a free-body diagram file for this problem. Determine the friction force acting on the block shown when the angle is 30 degrees and P=200N. us=0.3 (static friction) uk=0.2 (kinetic friction) The free-body diagram is how I started this solution. My equations became: Fx=0=200-Ncos

Rankine Cycle Problem

Rankine Cycle Problem. See attached file for full problem description. A supply of geothermal hot water is to be used as the energy source in an ideal Rankine cycle, with R-134a as the cycle working fluid. (See the diagrams below) Saturated vapor R-134a leaves the boiler at a temperature of 85°C, and the condenser tempera

Thermal Energy and Law of Increasing Entropy

(a) As an egg develops into a chicken, its contents become more ordered. Does this violate the law of increasing entropy? Why? (b) In the operation of a refrigerator, does thermal energy flow from hot to cold, or is it from cold to hot? Why?

17 Problems All in Mechanics: Force, tension, energy, vel...

Question 1: A packing crate is placed on a plane inclined at an angle of 35o from horizontal. If the coefficient of static friction between the crate and the plane is 0.65, will the crate slide down the plane? Justify your answer. Question 2: For the situation shown in the figure, what is the minimum coefficient of static fri

Derive hooke's law and find the "elastic entropy".

Polymers, like rubber, are made of very long molecules that tangle into a configuration that has lots of S. A crude model of a rubber band contains N links, all of equal length L, which can only point either left or right (2 possible states). The total length of the band is thus the net displacement from the first to the final

Pulley -block -force

Please see the attached file for full problem description. Please use work concepts for solution. The solution should involve integration from 2 to 0 distance block travel. Please detail any calculus involved - if the response doesn't involve calculus, I would still like to see it, but please explain why since I am fairl


1. During a violent thunderstorm, hail of diameter 1.0 cm falls directly downward at speed of 25m/s. There are estimated to be 120 hailstones per cubic meter of air. (a) what is the mass of each hailstone ( density = 0.92 g/cm^3) ? (b) Assuming that the hail does not bounce fine the magnitude of the average force on a flat roof

Newton's word problem

Jane, whose mass is 50.0kg, needs to swing accross a river(having width of D) filled with man-eating crocodiles to save Taezan from danger. She must swing into a wind exerting a constant horizontal force F on a vine having a length L and initially making an angle (theta) with the vertical. Taking D=50.0m F=110 N L=40.0m and

Tension of a spring with two masses on it.

There are two masses hanging down off the sides of a table connected with a spring between them. Describe what will happen and what value the spring scale S will read (a spring scale will read the tension in the wire.) in fig.1 below if m 1 = m 2 = 1 kg and if m 1 = 1.2 kg, m 2 = 1 kg. For the second case show your work and

Vectors and velocity: Landing speed for stone thrown from edge of a cliff

See attached file for a drawing. A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of v(0) = 17.4 m/s. The cliff is h = 42.4 m above a flat horizontal beach. With what speed does it land? I don't understand how the stone could land with anything but the speed of gravity. Can

A system of point charges

See attached file for graph. Four charges are placed at the corners of a square, where q is positive. Initially there is no charge in the center of the square. 1) Find the work, W required to bring the charge Qf from infinity and place it at the center of the square. 2) Find the magnitude of the electric force on th

Electrostatic force and gravitational force in equlibrium.

Two identical spheres of mass 0.1 g each carrying identical charges are suspended from the same point by two weightless threads each of length 1.3 m. They position themselves so that their centres are 1.0 m apart. Find the charge on each sphere.