RCFL MT Mechanical Mock Test - 9 - Mechanical Engineering MCQ

C.O.P decreases as work input increases. C.O.P =

For a fully developed laminar viscous flow through a circular pipe, the maximum velocity is equal to twice the average velocity.

i.e. V_max=2×V_avg

V_avg=0.5×V_max

Point to be remembered:

For the fully developed laminar flow through the parallel plates, the maximum velocity is equal to the (3/2) times of the average velocity.

i.e.

1. U-tube differential manometer

2. Inverted U-tube differential manometer

Decay of organic matter or putrefaction, the process whereby heterotrophic organisms, including some bacteria, fungi, saprophytic plants, and lower animals, utilize the remains of once-living tissue as a source of nutrition. The polysaccharides, lipids, nucleic acids, and proteins of dead tissue are broken down into smaller organic molecules, often by enzymes that are secreted into the external environment by the bacteria and fungi that are involved; the breakdown products are then readily absorbed by the heterotrophs and are used both as a source of building blocks for the synthesis of their own polysaccharides, lipids, nucleic acids, and proteins and as a source of chemical energy, obtained either by fermentation (in an anaerobic environment) or respiration (in the presence of oxygen). Often during the process of putrefaction, trace elements and nitrogen are released into the environment in forms suitable for uptake by higher plants; this is the basis for the use of decayed organic matter as fertilizer. The disagreeable odor produced as putrefaction takes place is caused by the formation of certain gases, including ammonia and hydrogen sulfide, and certain volatile amines, including putrescine and cadaverine, two products of the breakdown of protein by microorganisms.

In other words, heat is transferred by conduction when adjacent atoms vibrate against one another or as electrons move from one atom to another. Conduction is the most significant means of heat transfer within a solid or between solid objects in thermal contact. Fluids—especially gases—are less conductive.

• For an ideal monatomic gas (e.g., Helium, Argon, etc.), the adiabatic index is 5/3 or 1.67
• For diatomic gases, the adiabatic index is 7/5 or 1.4
• For polyatomic gases, the adiabatic index is even lesser than the monoatomic and diatomic gases
• Out of the given options, Helium is monoatomic, so it have the highest adiabatic index

Gravity does cause things to fall with increasing speed, but as they speed up, the viscous force due to air increases. Eventually, the viscous force due to air is enough to balance the force of gravity, so the acceleration stops, and the raindrop reaches a constant terminal velocity.

A mechanical equilibrium exists when all the mechanical forces within a system are balanced so that there is no acceleration.

A thermal equilibrium exists within a system when the temperature is uniform throughout so that there is no heat transfer within the system.

A phase equilibrium exists within a system when there are no phase transformations, such as melting, vaporization, etc., within the system.

A chemical equilibrium exists when there are no chemical reactions within the system.

Correct Answer :- a

Explanation : For 450 m head of water, Pelton wheel shall be used.

A Pelton turbine or Pelton wheel is a type of hydro turbine (specifically an impulse turbine) used frequently in hydroelectric plants. These turbines are generally used for sites with heads greater than 300 meters.

The water in a Pelton turbine is moving quickly and the turbine extracts energy from the water by slowing the water down, which makes this an impulse turbine.

As the ignition lag increases, the amount of fuel accumulated in the combustion chamber increases. When combustion actually takes place, an abnormal amount of energy is suddenly released, causing an excessive rate of pressure rise, which results in a knock.

The CI engine knock can be controlled by reducing the delay period. The delay is reduced by the following :

a. High charge temperature

b. High fuel temperature

c. Good turbulence

d. Injection of fuel just before TDC

To decrease the tendency of knock, it is necessary to start the actual burning as early as possible after the injection begins. In other words, it is necessary to decrease the ignition delay and thus decrease the amount of fuel present when the actual burning of the first few droplets starts.

The following are the differences in the knocking phenomenon of the S.I. and C.I. engines:

• In the S.I engine, the detonation occurs near the end of combustion, whereas in the C.I engine detonation occurs near the beginning of combustion

• The detonation in the S.I engine is of a homogeneous charge causing a very high rate of pressure rise and very high maximum pressure.

• In the C.I. engine, the fuel and air are imperfectly mixed, and hence the rate of pressure rise is normally lower than that in the detonating part of the charge in the S.I engine.

• In the C.I. engine, the fuel is injected into the cylinder only at the end of the compression stroke; there is no question of pre-ignition as in S.I. engine.

• In the S.I. engine, it is relatively easy to distinguish between knocking and non-knocking operations as the human ear easily finds the distinction.

The velocity of free vortex flow ∝ 1/r

∴ In a free vortex, velocity decreases with radius.

For a thin spherical pressure vessel, both longitudinal and hoop stress is the same and given as

MAXIMUM SHEAR STRESS THEORY (GUEST's or TRESCA's THEORY)

According to this theory, the elastic failure occurs when the greatest shear stress reaches a value equal to the shear stress at elastic limit in a simple tension test. This is used for ductile material

The word Vanity (Noun) means : too much pride in your own appearance, abilities or achievements; arrogance.
The word Humility (Noun) means: the quality of being humble. 

Covert means not openly acknowledged or displayed

Synonyms: secret, furtive, clandestine, surreptitious, stealthy

We cannot win in Afghanistan while Pakistan gives covert support to the Taliban
The climax of the book, a covert operation in Iran, is flaccid and unconvincing
Legally, it will be a deniable covert action which will put the CIA in the lead

∠DAC = ∠B + ∠C
(Exterior angle prop. of a Δ ABC)
According to question,
130° = 2A + 3A
5A = 130°
A = 26°
∴ ∠B = 52°; ∠C = 78°

The number π  is a mathematical constant. Originally defined as the ratio of a circle's circumference to its diameter, it now has various equivalent definitions and appears in many formulas in all areas of mathematics and physics. It is approximately equal to 3.14159. It has been represented by the Greek letter "π" since the mid-18th century, though it is also sometimes spelled out as "pi". It is also called Archimedes' constant.

4√6*3√24=4√6*3√2*√2*√*2*√3

=4√6*6√6

4*6*√6*√6=4*6*6=24*6=144

Daughter of grandmother = Aunt
Aunt’s only brother = Father

As, (4)² + 3 = 19

Similarly, (7)² + 3 = 52

According to the information given in the question, we can draw the following diagram.

BC = 24 m
FC = ED = 12 m
FC = 12 m
Thus point F is in the west w.r.t to point C and 12 m from point C.
Hence, the correct answer is "12 m west".

As Water of a River flows similarly water of Pool is Stagnant.

From the common explanation, we get Sagar scored 2nd lowest marks.

Hence, Option D is correct.

References:

Tarun scored more marks than Priyam but less than Rahul.

Sagar neither scored 3rd highest nor scored lowest marks.

Priyam scored more marks than Anurag.

Sagar scored less than Tarun, who scored 87 marks.

Inferences:

From the above references, we get the following arrangements

Rahul > Tarun (87) > Priyam > Sagar > Anurag

Given:

x + 1/x = 25

Concept Used:  

If x + 1/x = p then, x – 1/x = √(p² – 4)

Calculation:

It is given that x + 1/x = 25

 We know that if x + 1/x = p then, x – 1/x = √(p² – 4)

⇒ x – 1/x = √(25² – 4)

⇒ x – 1/x = √(625 – 4)

⇒ x – 1/x = √621

Persons: A, B, C, D, E and F

1) E is sitting immediate left to the B.

2) A is sitting fourth right to the B.

3) F is sitting between A and D.

4) Final Sitting arrangement.

Hence, “C” is sitting immediate left to the D.

The following factors have stimulated the globalisation process.

1.Improvement in transportation: In the last fifty years, there have been a lot of improvements in transportation technology. This has made faster delivery of goods across long distances possible, at lower costs.
2.Development in information and communication technology: Technology in the areas of telecommunication and computers has been advancing rapidly.
3.Telecommunication: Telecommunication facilities like telephone, telegraph, mobiles, fax are used to connect people in the world. This has been made possible due to satellite communication devices.
4.Internet: Internet also allows us to send instant electronic mail (e-mail) and talk (voice mail) across the world at negligible cost. Even the payment of money from one bank to another can be made through e-banking.