ems tutorial.pptx

7/22/2019 ems tutorial.pptx

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PREPARED BY EMS-CETSC

PRESENTED BY JOHN ERIC FERRANCO


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Introductory Concepts,

Definition and Units


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1.) 100g of water is mixed to 150g of alcohol(=790kg/m3). Calculate a) the specificgravity (RD) of the mixture; b) the specificvolume of the solution.


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2.) A 45cm cube of ice melts, the liquid wateris placed in a spherical container filling it. Ifthe specific volume of ice at 0C is1.094cm3/g and of water is 1.002cm3/g,

determine the diameter of the sphericalvessel used.


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3.) A two compartment vessel contains a fluidin each section. For the first compartment thefluid density is 1200kg/m3 and of the secondis 500kg/m3. The partition is removed and

the fluid mix. Determine the density of themixture if

a) the fluid masses are equal;

b) the fluid volume are equal.


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4.) A student on vacation went to scale Mt.Apo. His weight at the base of the mountain,where g=9.8m/s2 is 540N, on the top heweight 539.5N. Note that gravity acceleration

decreases by 0.003m/s2 per 1000m ascent.Find the height in meters if

a) Mt. Apo;

b) a point above the base where the weight ofan object decreases by 2%.


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5.) A balloon is descending with a constantacceleration of 3.5m/s2. The mass of theballoon with its basket and content is 80kg.What mass of the ballast must be released so

that the balloon will accelerate upward with aconstant acceleration of 3.5m/s2? Neglect airresistance.


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6.) A 40kN tank weighs 64kN when filled withkerosene and 70kN when filled with the samevolume of water. Find the specific gravity ofkerosene.


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7.) A solid cube material is 0.75cm on eachside. If it floats in oil of density 800kg/m3with 1/3 of the block out of oil, what is thedensity of the material of the cube?


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8.) The system shown is in equilibrium.Determine the diameter of the outside sphereif the submerged sphere has a diameter of35cm.


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9.) A block of wood with uniform horizontalsection floats in water with 20cm projectingabove the surface. The same block whenplaced in a body of oil (SG=0.8) floats with

18cm projecting above the oil surface.Determine the specific gravity of the wood.


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10.) Determine the maximum weight W whichcould be carried by the 45kg compositepiston shown, if the pressure of gas A is350kPa, gas B and C have pressure of 170

and 500kPa, respectively.


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11.) For the open manometer shown in thefigure, what is the pressure in kPa at A(a=30cm; b=48cm; RDHg=13.59)


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12.) For the differential manometer shown inthe figure, determine the pressure differencebetween points X and Y when: Fluid X and Y isbrine (RD=1.15), gage fluid is oil (RD=0.9)

and z=90cm.


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13.) CHALLENGE!A cubical block of wood 0.1m on a side andwith a density of 550kg/m3 floats in a jar ofwater. Oil with a density of 750kg/m3 ispoured on the water until the top of the oillayer is 0.035m below the top of the block.

a) How deep is the oil layer?

b) What is the gauge pressure at the blockslower face?


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Conservation of Mass and

Energy


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1.) Air flows through a compressor understeady flow condition. A suction:1=0.75m

3/kg, 1=30m/s. At discharge2=0.25m

3/kg, 2=40m/s. determine the

diameter ratio of the discharge pipe to that ofthe suction pipe.


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2.) A 200g apple is thrown from the edge of atall building with an initial speed of 20m/s.What is the change in kinetic energy of theapple if it strikes the ground at 50m/s?


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3.) What retarding force is required to stop a0.45 caliber bullet of mass 20g and a speedof 300m/s as it penetrates a wooden block toa depth of 2 inches?


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4.) A 40g rifle bullet is fired with a speed if300m/s into a ballistic pendulum of mass5kg suspended from a chord 1m long.Compute the vertical height through which

the pendulum rises.


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5.) A force F inclined at 30 with thehorizontal moves an object horizontally adistance of 8m. Determine the work done ifF=7.5x+0.4x2, where F is in Newton and the

x is in meter.


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6.) A wooden spherical ball with specificgravity of 0.42 and a diameter of 30cm isdropped from a height of 4.2m above thesurface of the water in a pool. If the ball

barely touches the bottom of the pool, whatis the water level in the pool at that point?


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7.) A project engineer notices the site of aformer sawmill along a river. Ruins of theoriginal dam used as a hydropower source isstill visible. The engineer decided to make

some measurements to determine themaximum power that can be generated if thesite were rehabilitated; the stream flow isfound to be 25m3/s and the change in

elevation is 4.87m. Determine the maximumpower that could be produced.


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8.) A 3kg block initially at rest us droppedfrom a height of 0.5m onto a spring whosescale is 2940N/m. Find the maximumdistance x that the spring will be

compressed. Assume g=9.8m/s2.


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9.) A gas contained in a piston cylinder hasfollowing initial properties: 3000kPa, 0.03m3.The gas is compressed during the processwhere PV1.4=C to a pressure of 9000kPa. The

heat transfer from the gas is 3kJ. Determinethe change in internal energy, neglectchanges in kinetic and potential energies.


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10.) Steam enters the turbine with a pressureP=4800kPa, u=2950kJ/kg, h=3300kJ/kg,and with a flow of 6kg/s. Steam leaves withh=2300kJ/kg, u=2100kJ/kg and P=22kPa.

The radiative heat loss is equal to 24kJ/kg ofsteam. Determine a) the power produced; b)the adiabatic power; c) the inlet specificvolume; d) the exit velocity if the exit area is

0.5m2.


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11.) Carbon Dioxide (=1.8kg/m3) having anenthalpy of 96.5kJ/kg enters a compressor. Itleaves with an enthalpy of 175kJ/kg. There is35kJ/kg of heat lost from the compressor as

CO2 passes through it. Neglecting changes inkinetic and potential energies, determine thepower required for a flow rate of 0.2225m3/s.


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12.) CHALLENGE! A centrifugal compressorcompresses 5.7m3/min of air from 83kPaa to620kPaa. The initial density is 1.27kg/m3 andthe final density is 4.8kg/m3. The inlet

suction line is 10cm in diameter and thedischarge line is 5cm in diameter. Determinea) the mass flow rate; b) the change in flowenergy between boundaries; c) the kinetic

energy change.


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Ideal Gas and Specific Heat


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1.) If the initial volume of an ideal gas iscompressed to one-half its original volumeand twice its original temperature, thepressure is?


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2.) A rigid vessel initially contains helium at105kPaa and 15C. Two kilograms of heliumare then added to the contents so that thefinal pressure and temperature are 200kPaa

and 20C. Determinea) the volume of the vessel;

b) the final mass of helium.


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3.) A rigid vessel initially contains hydrogenat 200kPaa and 20C. Two kilograms ofhydrogen are then pumped out so that thefinal pressure and temperature is at 105kPaa

and 15C. Determinea) the final mass of hydrogen;

b) the volume of the vessel.


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4.) A 1500L tank contains nitrogen at apressure of 400kPag and a temperature of320K. Later, because of a leak, it was foundthat the gage pressure has dropped to

320kPag and the temperature has decreasedto 300K; determine

a) the initial mass of nitrogen;

b) the remaining nitrogen;

c) the amount of nitrogen that has leakedout.


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5.) A bicycle pump is full of air atatmospheric pressure. The length of stroke ofthe pump is 45cm. At what part of the strokedoes the air begin to enter the tire in which

the gage pressure is 310kPag? Assumecompression is isothermal.


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6.) An air bubble rises from the bottom of awell where the temperature is 27C. Find thepercentage increase in volume of the bubbleif the depth of the well is 5m. Atmospheric

pressure is 101.528kPaa.


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7.) A 15cm diameter x 100cm lengthcylindrical steel vessel contained nitrogen at1315kPag and 28C. After some of thenitrogen was used the pressure and

temperature dropped to 480kPag and 22C.a) What proportion of nitrogen was used?

b) What volume would the used nitrogenoccupy at 1atm and 15.5C?


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8.) A 0.8m diameter sphere contains heliumat 20bar and 28C. How many cylindricaldrums 12cm in diameter and 70cm long,which is initially devoid of any gas, can be

filled to a pressure of 3bar at 18C? Assumethe helium in the sphere remains at 28C.


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9.) Complete the following ideal gas table:


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10.) 8kg of a gas, R=280J/kg.K andCv=0.78kJ/kg.K undergo a reversible non-flow constant pressure process fromV1=1.2m

3, P1=700kPaa to a state where

T2=480C. Finda)U,H, Q, Wnf;

b) if the process has been a reversible steadyflow type with P=0 and K=0, find W

sf.


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11.) A 0.064kg of octane vapor (MW=114) ismixed with 0.91kg of air (MW=29) in themanifold engine. The total pressure of themanifold engine is 86.1kPa and the

temperature is 290K. Assume octane behavesideally. What is the partial pressure of the airin the mixture in kPa?


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12.) 5kg of O2, 0.5kg of CO2 and 8.5kg of N2are mixed at constant temperature until themixture pressure is constant at 690kPaa.Determine

a) the partial pressure of each gas;b) the molecular weight of the mixture; and

c) the gas constant of the mixture.


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13.) It is desired to produce a gas mixturecontaining 35% by volume of CO2 and 65% byvolume of oxygen. If there is 1.4kg of CO2 inthe mixture, find

a) mass of O2 in the mixture;b) the gas constant of the mixture.


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14.) CHALLENGE! A valve joins a twocompartment adiabatic tank. 0.75 kg ofnitrogen dioxide at 4500kPaa and 400K iscontained in one compartment while 0.45kg

of air at 550kPaa and 300K is contained inthe other compartment. The valve is openedand the gasses mix. Determine

a) the gas constant for the mixture;

b) the final temperature and pressure of themixture.

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