UPSSSC JE Mechanical Paper 2 Mock Test - 1 - Mechanical Engineering MCQ

A cupola or cupola furnace is a melting device used in foundries that can be used to melt cast iron, Ni-resist iron, and some bronzes. The cupola can be made in almost any practical size.

Cast iron is made from pig iron, which is the product of melting iron ore in a blast furnace. Cast iron can be made directly from the molten pig iron or by re-melting pig iron, often along with substantial quantities of iron, steel, limestone, carbon (coke), and taking various steps to remove undesirable contaminants.

Parallel-crank four-bar linkage is used in the coupled wheels of a locomotive in which the rotary motion of one wheel is transmitted to the other wheel.

Example:

Coupling rod of a locomotive

The thermodynamic properties, which depend on the end states as well as the path followed, are known as path functions like heat and work.

So a minimum of four links is necessary to form a kinematic chain.

What are the other types of Extrusion?

Extrusion is classified in general into four types. They are Direct extrusion, indirect extrusion, impact extrusion, and hydrostatic extrusion.

Direct extrusion, also called forward extrusion, is when the billet moves along the same direction as the ram and punch do. The sliding of the billet is against a stationary container wall. Friction between the container and billet is high.

Indirect extrusion (backward extrusion) is a process in which a punch moves opposite to that of the billet. Here there is no relative motion between container and billet. Hence, there is less friction, and hence reduced forces are required for indirect extrusion.

In hydrostatic extrusion, the container is filled with fluid. Extrusion pressure is transmitted through the fluid to the billet. Friction is eliminated in this process because there is no contact between the billet and container wall.

Impact extrusion: Hollow sections such as cups, toothpaste containers are made by impact extrusion. It is a variation of indirect extrusion. The punch is made to strike the slug at high speed by impact load. Tubes of small wall thickness can be produced. Usually, metals like copper, aluminium, lead are impact extruded.

Efficiency of heat engine (ɳ) = (T_H – T_L) / _TH = W_out/ Q_in

T_H = Temperature of the hot reservoir

T_L = Temperature of the cold reservoir

Q_in = Heat input to the engine

W_out = Work output from the engine

Calculation:

TH = 2127°C = 2127 + 273 = 2400 K

T_L = 27°C = 27 + 273 = 300 K

Efficiency will be maximum when the engine is reversible.

The velocity of a body moving with uniform acceleration

The body is undergoing constant acceleration. Acceleration is the rate of change of velocity versus time. Velocity is a vector consisting of magnitude (speed) and direction. In a uniform circular motion, the speed is fixed, the direction is constantly changing; therefore, the velocity changes.

In that case, both v and a are negative. The plus and minus signs give the directions of the accelerations. If acceleration has the same sign as the change in velocity, the object is speeding up. If acceleration has the opposite sign of the change in velocity, the object is slowing down.

• Flow separation occurs when the boundary layer travels far enough against an adverse pressure gradient that the speed of the boundary layer relative to the object falls almost to zero.
• It has been observed that the flow is reversed in the vicinity of the wall under certain conditions.

• A favourable pressure gradient is one in which the pressure decreases in the flow direction (i.e., dp/dx < 0)="" />
• It tends to overcome the slowing of fluid particles caused by friction in the boundary layer.
• This pressure gradient arises when the freestream velocity U increases with x, for example, in the converging flow field in a nozzle.
• On the other hand, an adverse pressure gradient is one in which pressure increases in the flow direction (i.e., dp/dx > 0)
• It will cause fluid particles in the boundary layer to slow down faster than that due to boundary-layer friction alone.
• If the adverse pressure gradient is severe enough, the fluid particles in the boundary layer will actually be brought to rest.
• When this occurs, the particles will be forced away from the body surface (a phenomenon called flow separation) as they make room for following particles, ultimately leading to a wake in which flow is turbulent.

Taking log

log(p_2/p₁)/log(v₁/v₂)

In shaping and planning operations, straight and flat surfaces are created. In shaping operation, the speed motion is accomplished by moving the cutting tool, while in planning, the motion is accomplished by the workpiece. Shaping is performed in a machine tool called a shaper, whereas the machine tool for planning is called a planer. The slotting process is identical to shaping except that the motion of the ram is vertical instead of horizontal.

The size of the shaper is specified by the maximum length of stroke or cut it makes. The maximum stroke length of the shaper is 900 mm.

Resilience is defined as the capacity of a strained body for doing work on the removal of the straining force.

Proof resilience is defined as the maximum strain energy stored in a body. So, it is the quantity of strain energy stored in a body when strained up to an elastic limit (ability to store or absorb energy without permanent deformation).

Modulus of resilience is defined as proof resilience per unit volume. It is the area under stress–strain curve up to the elastic limit.

Example to fire tube boilers:

• Cornish boiler

• Cochran boiler

• Locomotive boiler

• Lancashire boilerScottishh marine boiler

Water Tube Boiler: In this boiler, water is present inside the tubes, and the hot flue gases surround them. They are high-pressure boilers. The operating pressure is about 250 bar.

Examples of water tube boilers:

• Stirling boiler

• Babcock and Wilcox boiler

• Yarrow boiler

• La mont boiler

• Loeffler boiler

• Velox boiler

The angle of inclination of the plane at which the body begins to move down the plane, is called angle of repose.

The neutral flame has a one-to-one ratio of acetylene and oxygen. It obtains additional oxygen from the air and provides complete combustion. It is generally preferred for welding. The neutral flame has a clear, well-defined, or luminous cone indicating that combustion is complete

Atom

An atom is the smallest particle of an element, having the same chemical properties as the bulk element. The first accurate theory explaining the nature of matter was Dalton's Atomic Theory: 1. All matter is composed of atoms, and atoms are indivisible and indestructible.

The period T =

So the statement the time period is proportional to its length is wrong.

1. When two equal vectors A are inclined 90° then, resultant = √2A

2. When the angle between two equal vectors A is 120°, then resultant = A

3. When the angle between two equal vectors A is 180°, then resultant = 0

4. When the angle between two equal vectors A is 60°, then resultant = √3A

Now, come to the question,

Your question is " two equal force inclined at 120°,

So, resultant = P

Just 1 second is enough for answering.

Well you know method is Resultant = √{P² + P² + 2P.P Cos 120°} = P

So, option (C) is correct.

The non-flow work done by the system (only on the quasi-static process) is given by:

W_non−flow=mathopsmallintlimits₁²pdV

Work done in a flow process (any process):

W_{flow−process}=−mathopsmallintlimits₁²VdP

Cavitation is the formation of gas bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure i.e., low pressure.

Cavitation is the phenomenon of the formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below the vapour pressure of the fluid and sudden collapsing of these bubbles in the region of higher pressure.

In centrifugal pumps, the cavitation may occur at the inlet of the impeller of the pump or at the suction side of the pumps, where the pressure is considerably reduced.

Hence if the pressure at the suction side of the pump drops below the vapour pressure of the liquid then cavitation may occur.

When the axes of the first gear and the last gear are co-axial, then the gear train is known as a reverted gear train. The reverted gear trains are used in automotive transmissions, lathe back gears, industrial speed reducers, and in clocks (where the minute and hour hand shafts are co-axial).

The epicyclic gear trains are useful for transmitting high-velocity ratios with gears of moderate size in a comparatively lesser space. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist-watches, etc.

Correct Answer :- c

Explanation : Both zero and changes sign is the correct answer. Because when sf changes sign from max to min or vice versa, it will come to a point when sf will be zero.

So according to the given options "changes sign" is the correct answer.

The function of a governor is to maintain the speed of the engine within specified limits whenever there is a variation of load.

The speed of an engine varies in two ways

1. During each revolution or cyclic variation

2. Over a number of revolutions.

During each revolution or cyclic variation, the speed of the engine varies due to variation in output torque of the engine during a cycle. It is regulated by a flywheel mounted on the shaft.

Over a number of revolutions, the speed of the engine varies due to variation in load upon the engine, and the speed is maintained by mounting a governor.

In uniform gravity, it is the same as the centre of mass. For regular-shaped bodies, it lies at the centre of that particular body. Hence for a cylinder centre of gravity lies at the midpoint of the axis of the cylinder.

A body is in equilibrium when the vector sum of external forces and moments is zero.

Types of equilibrium:

Static equilibrium: In static equilibrium, the number of forces acting on a body causes no change in the state of the rest of the body.

∑FX = 0, ∑FY = 0

Dynamic equilibrium: According to D Alembert’s principle, the resultant of all the external forces that are acted on the body and the moment of all the forces are equal to zero, then the body is said to be in dynamic equilibrium.

∑FX = 0, ∑FY = 0 and ∑M = 0