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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

Essentially,

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

### PV Diagram to Solve Total Work and Heat Transfer

A confined quantity of air undergoes two thermodynamic processes departing from an initial equilibrium state where the temperature is 20°C, the absolute pressure is 1bar, and the volume is 0.2m3. First, the volume of the system is doubled through an isobaric process. Then, the volume is reduced back to the initial value through

### buoyant force

An object falls off of a pier and into the ocean (sea water) where it displaces a total volume of 3.8 cubic meters of sea water. What is the buoyant force acting on the object in newtons? You will need to use the mass density form of the buoyant force equation in order to work the problem in the mks system.

### 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

### Buoyant force problem for object that falls off a pier (mass density)

An object falls off of a pier and into the ocean (sea water) where it displaces a total volume of 3.6 cubic meters of sea water. What is the buoyant force acting on the object in newtons? You will need to use the mass density form of the buoyant force equation in order to work the problem in the mks system.

### 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

### Determining Energy, Work and Magnitude of Force

1. From the top of a 75.0 m high building, a 1.00 kg ball is thrown directly downward with an initial speed of 8.00 m/s. If the ball reaches the ground with a speed of 32.0 m/s, the mechanical energy lost to friction is equal to: a. 0 J b. 255 J c. 480 J d. 735 J e. 767 J 2. A 15-kg child stroller is moving towards you

### 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.

### Sketch a PV Diagram and Find the Work

1) Sketch a PV diagram and find the work done by the gas during the following stages. (Draw the PV diagram on paper. Your instructor may ask you to turn in this work.) (a) A gas is expanded from a volume of 1.0 L to 2.9 L at a constant pressure of 2.8 atm. work done______J (b) The gas is then cooled at constant volume unt

### A Block on a Frictionless Surface and a Compressed Spring

A 1.9kg block is released from rest and allowed to slide down a frictionless surface and into a spring. The far end of the spring is attached to a wall. The initial height of the block is 0.40m above the lowest part of the slide and the constant is 387N/m. 1) What is the speed of the block at a height of 0.25m above the base

### Pully system with kinetic and static friction

A 30.5 kg block is connected to an empty 1.00 kg bucket by a cord running over a frictionless pulley (Fig. 4-57). The coefficient of static friction between the table and the block is 0.470 and the coefficient of kinetic friction between the table and the block is 0.320. Sand is gradually added to the bucket until the system jus

### 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?

### The Charpy testing machine: Energy absorbed

Please see the attached file and show the work.

### 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

### Electric Field and It's Potential

See attached file for full problem description. 1. A square of side a has charge + Q and -Q alternating from one corner to the next, as shown. Find the potential energy for the system of charges. 2. Electric potential is a scalar quantity. 3. The direction of an electric field is from higher to lower potential. 4. A

### Work done by person

A person carries a mass of 10 kg and walks along the +x-axis for a distance of 100m with a constant velocity of 2 m/s. What is the work done by this person? 0 J 20 J 200 J None of the other choices is correct.

### 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

### Work, Internal Energy, Heat

While running, 5.2 X 10^5 Joules of work is done by a jogger and 4.1 X 10^5 Joules of heat is lost by the jogger. What is the change DU in the jogger's internal energy? ___.___ X 10^5 Joules

### Calculate Efficiency of a system consisting of a cylinder sealed by a piston

A system consisting of a cylinder full of gas, sealed by a piston, is alternately loaded, heated, unloaded and then cooled back to it's original state. If 211.2 Joules of work are done, and if 448.8 J of thermal energy are taken out or lost during cooling and other processes, then what is the efficiency of the system?