A solid and hollow shaft, connected by a coupling, transmit power. The outside diameters of the shafts are the same and the inside diameter of the hollow shaft is 75% of its outside diameter. The solid shaft is three times as long as the hollow shaft. Take the modulus of rigidity for both shafts as 80 GPa. (a) If the angle of twist for the solid shaft is 1 degree, find the angle of twist for the hollow shaft. (b) If the maximum shear stress for the solid shaft is 30 MPa, find the maximum stress in the hollow shaft.
In: Mechanical Engineering
A compound thin cyclinder has a common diameter of 100 mm and the inner cylinder has a thickness of 2.5 mm. The radial pressure between the two cylinders is 200 kPa and the difference between the two common diameters before shrinkage was 4.305×10-3 mm. Determine (a) the thickness of the outer cylinder (b) the resultant hoop stresses in both cylinders if the compound cylinder is subjected to an internal pressure of 180 kPa. (E = 200 GPa)
In: Mechanical Engineering
There has been a lot of interest about replacing gasoline with ethanol, but is this really a good idea? We’re going to compare a blend of ethanol (70% ethanol and 30% gasoline by volume) to gasoline. Calculate the lower heating value (LHV) of a 70% ethanol/30% isooctane mixture in terms of kJ/mol of fuel. Assume complete combustion. How does this compare to the tabulated value for gasoline (isooctane)? Assuming a 20% thermal efficiency, if you need to get 100 kW of power from an engine, how much of each fuel (in mol/s) do you need? If you have a stoichiometric mixture of the ethanol/gasoline blend and air in your 100 kW engine, how much CO2 are you emitting in g/s? How does this compare to the same engine running a stoichiometric mixture of 100% gasoline and air?
In: Mechanical Engineering
6. The power of a test in hypothesis testing is given by:
Select one:
a. 1+ß
b. 1-ß
c. (1+ß)/ ( 1-ß)
d. 1/ß
7. The power of a test in hypothesis testing is given by:
Select one:
a. 1+ß
b. 1-ß
c. (1+ß)/ ( 1-ß)
d. 1/ß
8. Which of the following is a disciplined procedure for systematic evaluation of the impact of potential failures and thereby determining a priority of possible actions that will reduce the occurrence of such failures?
Select one:
a. Pareto diagrams
b. Matrix plot
c. FMECA
d. Fish bone diagram
9. The difference between the company’s level and that of the best practice for that performance measure is identified as the gap. The analysis that focuses on methods and processes to reduce that gap and thereby improve the company’s competitive position is known as____________ .
Select one:
a. Balanced scorecard analysis
b. None of these
c. Gap analysis
d. QFD
10. Vendor certification occurs when the vendor has reached the stage at which it consistently meets or exceeds the purchaser’s expectations?
Select one:
a. true
b. false
In: Mechanical Engineering
26. Select the odd one out
Select one:
a. Zone control
b. Paint strips
c. Imbedded wire
d. dead reckoning
27. An AGV has an average speed of 50 m/min. how much distance it can travel in an hour given that it is working in a factory layout in which it has availability factor of 0.9 and traffic factor of 0.95
Select one:
a. 3 km
b. 2.5 km
c. 3.5 km
d. 2 km
28. In which of the automated storage systems the storage chambers moves
Select one:
a. Transfer line
b. Dollies
c. Carousel
d. ASRS
29. which of the following G code is used for giving cutter radius comensation
Select one:
a. G44
b. G40
c. G41
d. G43
30. Which of the device make it possible to use a single microprocessor to capature data from n number of sensors
Select one:
a. Operational amplifiers
b. ADC
c. Multiplexer
d. DAC
In: Mechanical Engineering
a It was observed that natural frequency of a torsional pendulum when vibrating in vacuum is 280Hz. But, the damping frequency is 220Hz when the same pendulum is dipped in an oil of specific gravity 0.9. Find the value of damping factor of the oil. (Hint: There is no damping in case of vacuum)
b A vibratory system weighing 1.5tonnes has the the following successive amplitudes: 5.00, 3.15, 2.00, 0.75, 0.50, 0.30, 0.20, 0.10 mm respectively. The time gap between two successive cycles is 0.64s. Draw the displacement-time graph of the system. Also, calculate the damping ratio, natural frequency and stiffness of the associated spring
In: Mechanical Engineering
11. Solubility of O2 _______________with the increase in temp.
Select one:
Increases
Decreases
No Change
12. For isokinetic sampling, static pressure at nozzle tip should be _____________than that of free stream
Select one:
Less
More
Equal
13The DO level in the water _________ from 12.30 pm to 3.30pm.
Select one:
Increasses
Decreases
Remains same
14. Which of the following particulate matter are collected in collection devices in steel industry?
Select one:
Oil
Acetic acid
Iron oxide
Boron
15. Eutrophication causes decrease in __________
Select one:
Dissolved hydrogen
Dissolved salts
Dissolved oxygen
All of the above
In: Mechanical Engineering
1 In Oxygen-Sag Curve, at the critical point, the rate of reaeration becomes ________ the rate of Deoxygenation
Select one:
Double
Equal to
Half
2. In general, adsorption of a gas on solid surface is_________process
Select one:
Endothermic
Exothermic
None
3. Which of the following tests can be performed in relatively shorter period of time?
Select one:
TOC
BOD
COD
All require same time
4. In Claus process, H2S is converted to____________
Select one:
SO3
disulphide
Elemental Sulphur
5. Which of the following Samples provide more meaningful data when the composition of waste varies with either time or flow?
Select one:
a.Grab
b.Composite
Both 'a' and 'b'
None
In: Mechanical Engineering
Saturated water vapor at 1000 kPa is throttled to 100 kPa. The velocity of the steam remains constant through the process. Determine the exit temperature of the water vapor. I know this is already awnsered in a solution for 1st edition but can someone help me understand what they do and how they picked the numbers they did from some table to get the exit temperature?
In: Mechanical Engineering
In a connection using 5/8-inch Φ (UNF-18, SAE Grade 8) bolts, each bolt is subjected to a varying axial load between 10 Kips to 20 Kips. Bolts can be preloaded between 0% (none) and 100%, at 10% intervals, of their proof strength.
What range of preload is ideal so that the fatigue life of this joint is infinite without join separation?
Use Modified Goodman Criteria for fatigue and show calculations for the preload levels between 0% and 100% (or at least the two cases of 0% and 50%). Calculate max stress and factor of safety for infinite life vs. preload as % of proof strength; find gross yielding & joint separation of bolts; then establish a workable range and ideal value for preload.
In: Mechanical Engineering
1. Explain the difference between Plane Stress problem and Plane Strain Problem. Give an example.
2. What is the displacement boundary condition you would like to apply after cutting through the symmetric line?
3. What are the FEA results we would be interested in 2-D stress-strain analysis?
In: Mechanical Engineering
4. What are the material properties to be input in 2-D stress-strain analysis?
5. What are the two sources of errors in FEA modeling? Explain.
In: Mechanical Engineering
An oil cooler for a large diesel engine is to cool engine oil
from 60 to 45 °C, using seawater at an inlet temperature of 20 °C
with a temperature rise of 15 °C. The design heat load is 140 kW,
and the mean overall heat transfer coefficient based on the outer
surface area of the tubes us 70 W/m2°C. Calculate the heat transfer
surface area for single pass (a)- counter flow and (b)- parallel
flow arrangements.
In: Mechanical Engineering
Air enters the compressor of an ideal air standard Brayton cycle at 100 kPa and 290 K with a mass flow rate (m⋅) of 6 kg/s. The compressor pressure ratio is 10. The turbine inlet temperature is 1500 K. If a regenerator with an effectiveness of 70% is incorporated in the cycle, determine (a) the thermal efficiency (ηth,Brayton) of the cycle. Use the PG model for air. (b) What-if Scenario: What would the thermal efficiency be if the regenerator effectiveness increased to 90% ?
In: Mechanical Engineering
What is the accuracy and precision of using a ball screw of 0.5 diameter in designing a table of motion that is 48 inch in x and y direction?
In: Mechanical Engineering