Engineering Questions with Answers - Multiple Choice Questions
Strength of Materials MCQs Thin Spherical Shells Under Stress
__________ stress does not exceed the permissible tensile stress for the shell material.
Explanation: Circumferential (hoop) stress does not exceed the permissible tensile stress (Pt) for the shell material
t = pd/2fh.
To determine hoop stress, efficiency of _________ is to be considered.
a) Construction joint
b) Transverse joint
c) Longitudinal joint
d) Rivet joint
Explanation: To find hoop stress, the efficiency of longitudinal joints to be considered.
fh=pd/2t nl; Where
fh = hoop stress
p = internal pressure
t = thickness of metal
d = diameter
nl = efficiency of longitudinal joint.
Cast Iron pipes are being joined a _________
a) Flange joint
b) Expansion joint
c) Socket and spigot joint
d) Simplex joint
Explanation: Cast iron pipes are being joined socket and spigot joint. The enlarged end is called socket while the normal end is called spigot. The spigot is fitted into the socket.
Bell joint is also known as ___________
a) Spigot joint
b) Expansion joint
c) Socket joint
d) Simplex joint
Explanation: Socket and spigot joint sometimes called bell and spigot joint. It is flexible and allows the pipes to be laid on flat curves without use of specials.
Which of the following joint is a simplex joint?
a) Flanged joint
b) Socket and spigot joint
c) AC pipe joint
d) Expansion joint
Explanation: AC pipes are joined by means of a special type of coupling called simplex joint which consists of a pipe and two rubber rings.
The mortise and tenon are provided in __________ joint.
c) A C pipe
Explanation: The concrete pipes are provided with mortise at one end and a suitable tenon each other and the mortise and tenon are tightly set by placing concrete mortar.
________ head should be higher than working head in a hydraulic test.
Explanation: In a hydraulic test, to detect leakage the lower end of pipe is plugged and filled with water. The hydrostatic head should be higher then working head for 2 hours for ensuring leakage.
Leakage should be nil or minimum by following equation Q = ___________ × ND (P)1/2.
Explanation: To ensure nil leakage, the equation to be followed is Q = 2/3300 ND × (P)1/2.
Q = allowable leakage (l/h)
N = number of joints
D = pipe diameter
P = total pressure applied.
_______ is used to magnify the sound for detecting leakage.
Explanation: Leakages can be detected by the sounding rod method. In this method, sound can be magnified by Sonoscope. The rod is pulled up and observed whether the point is dry or most as it indicates leakage.
Which of the following is not a leakage detection method?
a) Direct observation
b) By plotting HGL
c) Pipe corrosion
d) Sounding rod
Explanation: The term pipe corrosion is used to indicate the loss of pipe material due to the action of water. The metal chiefly concerned with corrosion of iron and steel, of which mains and distribution pipes are usually composed.
Which of the following is not a cause of corrosion?
a) The cathodic reaction
c) Reaction of metal ions
d) Proper pipe material
Explanation: It is one of the steps in the prevention of corrosion, the pipe material if metallic should be able to resist that dissolve effect of water.
A pipe sunk into the ground to draw the underground water is known as ___________
a) An open well
b) A tube well
c) An artesian well
d) An infiltration well
Explanation: Tube wells are the wells made by drilling holes in to the ground encased with pipes and strainers. The diameter varies between 0.15 to 0.6 m.
Which of the following well is also known as flowing well?
a) Gravity well
b) Artesian well
c) Drilled wells
d) Driven wells
Explanation: Artesian Wells derives water from confined aquifers under pressure. As a result, ground water flows from the well such a well is known as flowing well.
The water bearing strata is known as _________
a) An aquifer
b) An aquiclude
c) An aquifuge
d) An aquitard
Explanation: An aquifer is defined as a saturated bed or geologic formation which yields water in significant quantities Eg. Sand bed.
The difference in levels of water in a well before and after pumping is called ________
a) Cone of depression
c) Draw down
d) Water table
Explanation: When water is pumped from a well, the water around the well under the action of head caused due to difference in level of the original water table and lowered water table. This head is known as draw down or depression head.