All India Mechanical Engineering Group

Consider a bar of length L, breadth B and thickness t subjeced to an axial pull or tension P. The resulting volumetric strain will be equal to
  • a)
    ∈ (1 -2v)
  • b)
    2∈ (1 - v )
  • c)
    ∈ (1 + 2v)
  • d)
    3 ∈ v
Correct answer is option 'A'. Can you explain this answer?

Saranya Saha answered  •  13 hours ago
Explanation:
The volumetric strain (ε_v) is defined as the change in volume per unit volume of the material. When a bar is subjected to axial tension, it experiences elongation in the axial direction and contraction in the lateral directions.

Formula:
ε_v = ε_x + ε_y + ε_z
Where:
ε_x = Strain in x-direction
ε_y = Strain in y-direction
ε_z = St
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Assume that the two 2 mm thick steel sheets are being sport welded at a current of 5500 A and current - flow time t = 0.15s. Using electrodes 6 mm in diameter, estimate the amount of heat generated in resistance spot welding. (Take RC = 250 μΩ)
  • a)
    1032 J
  • b)
    1120 J
  • c)
    995 J
  • d)
    1134 J
Correct answer is option 'D'. Can you explain this answer?

Saranya Saha answered  •  13 hours ago
Given data:
- Thickness of each steel sheet (t): 2 mm
- Current (I): 5500 A
- Time (t): 0.15 s
- Diameter of electrodes (d): 6 mm
- Resistance of contact (RC): 250 μΩ

Calculating the heat generated:
1. Calculate the resistance of each spot weld:
- Resistance (R) = RC * t
- R = 250 μΩ * 0.15 s = 37.5 μΩ
2. Calculate the heat ge
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The pump to be used for pumping highly viscous fluids belongs to the category of
  • a)
    screw pump
  • b)
    turbine pump
  • c)
    plunger pump
  • d)
    centrifugal pump
Correct answer is option 'A'. Can you explain this answer?

Manoj Pillai answered  •  16 hours ago
Types of Pumps for Pumping Highly Viscous Fluids
There are different types of pumps that can be used for pumping highly viscous fluids, but the most suitable one for this application is a screw pump. Below are the reasons why screw pumps are the preferred choice:

Screw Pump
- Screw pumps are designed to handle viscous fluids efficiently due to their unique pumpin
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De Laval turbine is
  • a)
    single rotor impulse turbine
  • b)
    velocity compounded impulse turbine
  • c)
    pressure compounded impulse turbine
  • d)
    impulse reaction turbine
Correct answer is option 'A'. Can you explain this answer?

Dipika Bose answered  •  17 hours ago
De Laval turbine
De Laval turbine is a type of single rotor impulse turbine.
  • Single rotor impulse turbine: De Laval turbine falls under this category as it operates based on the principle of impulse. The fluid (steam or gas) is directed onto the rotor blades, causing a change in momentum and generating mechanical energy. It does not involve any pressure drop in the ... more



Operating Principle
  • Impulse Turbine: In an impulse turbine like De Laval turbine, the fluid's pressure energy is converted into kinetic energy by expanding through a nozzle. The high-velocity fluid then impacts the rotor blades, transferring its momentum and causing the rotor to rotate.



Characteristics
  • Efficiency: Single rotor impulse turbines like De Laval turbines are known for their high efficiency in converting fluid energy into mechanical work.
  • Simple Design: De Laval turbines have a relatively simple design compared to reaction turbines, making them easier to manufacture and maintain.
  • High Speed: Due to the impulse nature of operation, De Laval turbines can achieve high rotational speeds, making them suitable for certain applications requiring high-speed operation.


In conclusion, De Laval turbine is a single rotor impulse turbine that operates based on the principle of impulse to convert fluid energy into mechanical work efficiently. Its simple design and high-speed capabilities make it a favorable choice for certain industrial applications.

In blanking operation the clearance is provided on
[ME 2002]
  • a)
    The die
  • b)
    The punch
  • c)
    Both die and punch equally
  • d)
    Neither the punch nor the die
Correct answer is option 'B'. Can you explain this answer?

Dishani Desai answered  •  18 hours ago
Blanking Operation Clearance:
Blanking operation involves cutting a piece of material from a larger sheet or strip. It is important to provide clearance in the operation to ensure smooth and accurate cutting.

Clearance on the Punch:
- In blanking operation, the clearance is typically provided on the punch.
- The clearance on the punch allows for easy remova
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We have two types of coefficient of friction, one is coefficient of static friction and the other one is the coefficient of the kinetic friction.
  • a)
    True
  • b)
    False
Correct answer is option 'A'. Can you explain this answer?

Siddharth Menon answered  •  yesterday
Explanation:

Types of Coefficient of Friction:
- Coefficient of Static Friction: This type of friction occurs when two surfaces are at rest relative to each other. It is the maximum friction force that must be overcome before the object starts moving.
- Coefficient of Kinetic Friction: This type of friction occurs when two surfaces are sliding again
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6 : The coefficient of artificial variable in the objective function of maximization problem is?

Devansh Nambiar answered  •  yesterday
Coefficient of Artificial Variable in Objective Function
The coefficient of an artificial variable in the objective function of a maximization problem is typically set to zero. This is done to ensure that the artificial variables do not influence the optimization process and only serve the purpose of helping in finding a feasible solution.

Explanation
- Object
... more: The objective function in a linear programming problem represents the quantity that needs to be maximized or minimized. It is a linear combination of decision variables and constants.
- Artificial Variables: Artificial variables are introduced in the initial tableau to help in finding an initial feasible solution for the linear programming problem. They are used when the constraints of the problem do not form a feasible region.
- Coefficient in Objective Function: The coefficient of an artificial variable in the objective function is typically set to zero because the goal is to minimize or maximize the actual objective of the problem, not the artificial variables. Setting the coefficient to zero ensures that the artificial variables do not impact the optimization process.
- Maximization Problem: In a maximization problem, the objective is to maximize the value of the objective function. The artificial variables are only used to help in finding a feasible solution, and their coefficients are set to zero in the objective function.
In conclusion, the coefficient of an artificial variable in the objective function of a maximization problem is set to zero to ensure that the optimization process focuses on maximizing the actual objective of the problem, rather than the artificial variables.

The flow of fluid through a pipe is laminar when
  • a)
    the fluid is ideal
  • b)
    the fluid is viscous
  • c)
    the Reynolds number is less than 2000
  • d)
    there is considerable lateral dispersion of smoke or dye injected into the flow stream '
Correct answer is option 'C'. Can you explain this answer?

Arshiya Dey answered  •  yesterday
Explanation:

Laminar Flow:
- Laminar flow is a type of fluid flow characterized by smooth and orderly movement of fluid particles.
- In laminar flow, the fluid flows in parallel layers with minimal mixing between layers.

Reynolds Number:
- The Reynolds number is a dimensionless quantity used to predict the flow regime of a fluid in a pipe.<
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For the rolling of the body right handed coordinate system means (consider the mentioned axis to be positive)?
  • a)
    Thumb is z-axis, fingers curled from x-axis to y-axis
  • b)
    Thumb is x-axis, fingers curled from z-axis to y-axis
  • c)
    Thumb is y-axis, fingers curled from x-axis to z-axis
  • d)
    Thumb is z-axis, fingers curled from y-axis to x-axis
Correct answer is option 'A'. Can you explain this answer?

Raj Kumar answered  •  yesterday



Explanation:

Thumb is z-axis, fingers curled from x-axis to y-axis
- In a right-handed coordinate system, the thumb represents the positive z-axis.
- When rolling the body in this coordinate system, the fingers curl from the positive x-axis to the positive y-axis.
- This motion follows the right-hand rule, where the thumb points
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The heat treatment process used for hardening of steel is
  • a)
    tempering
  • b)
    quenching
  • c)
    normalising
  • d)
    annealing
Correct answer is option 'B'. Can you explain this answer?

Raghav Saini answered  •  yesterday
Quenching:
Quenching is a heat treatment process used for hardening steel. It involves heating the steel to a specific temperature and then rapidly cooling it in a quenching medium, such as oil or water. This rapid cooling changes the structure of the steel, making it harder and stronger.

Process:
- The steel is heated to a temperature above its critical point, w
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The slenderness ratio of a section is
  • a)
    directly proportional to the radius of gyration
  • b)
    directly proportional to the moment of inertia
  • c)
    inversely proportional to the area
  • d)
    inversely proportional to the radius of gyration
Correct answer is option 'D'. Can you explain this answer?

Sharmila Chauhan answered  •  yesterday
Explanation:
Slenderness ratio of a section is defined as the ratio of the effective length of the column to the least radius of gyration of its cross-section. It is denoted by the symbol "λ".

Slenderness Ratio and Radius of Gyration:
- The slenderness ratio of a section is inversely proportional to the radius of gyration.
- This means that as the radius of
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A spherical pressure shell 3.8 meters diameter and 3 mm thick is subjected to an internal pressure ‘P’. The elastic limit of the shell material in simple tension is 260 MPa. The factor of safety is to 2.8. The internal pressure, if the failure of shell is to be prevented, according to maximum shear stress theory is
  • a)
    1.78 bar
  • b)
    2.932 bar
  • c)
    5.86 bar
  • d)
    2.33 bar
Correct answer is option 'B'. Can you explain this answer?

Sharmila Chauhan answered  •  yesterday
Calculation of Internal Pressure:
Given data:
- Diameter (D) = 3.8 meters
- Thickness (t) = 3 mm
- Elastic limit (σ) = 260 MPa
- Factor of safety (FoS) = 2.8

Step 1: Calculate hoop stress (σ_h):
Hoop stress is given by the formula: σ_h = P * D / (2 * t)
Substitute the values: σ_h = P * 3.8 / (2 * 0.003) = 633.33P

Step 2: Cal
... more
Maximum shear stress is given by the formula: τ_max = σ_h / 2
Substitute the value of hoop stress: τ_max = 633.33P / 2 = 316.67P

Step 3: Calculate allowable shear stress (τ_allow):
Allowable shear stress is given by the formula: τ_allow = σ / FoS
Substitute the values: τ_allow = 260 MPa / 2.8 = 92.857 MPa

Step 4: Equate maximum shear stress to allowable shear stress:
316.67P = 92.857
Solve for P: P = 92.857 / 316.67 ≈ 0.292 bar
Therefore, the internal pressure required to prevent the failure of the shell according to the maximum shear stress theory is approximately 2.932 bar (option B).

If number of rivets subjected to single shear per pitch length is 2 and those subjected to double shear per pitch length are 3, then find the shear resistance of rivets is diameter of rivets is 20mm and permissible shear 60N/mm².
  • a)
    None of the listed
  • b)
    146.1kN
  • c)
    150.7kN
  • d)
    140.2kN
Correct answer is option 'C'. Can you explain this answer?

Sharmila Chauhan answered  •  yesterday
Shear Resistance Calculation for Rivets:

Given data:
- Number of rivets subjected to single shear per pitch length = 2
- Number of rivets subjected to double shear per pitch length = 3
- Diameter of rivets = 20mm
- Permissible shear stress = 60N/mm²

Calculations:
1. Area of each rivet in single shear = π*(diameter/2)² = π*(20/2)²
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The singular solution of the differential equation y = px + p3 where p = dy/dx , is
  • a)
    4y3 + 27x2 = 0
  • b)
    4x3 + 27y3 = 0
  • c)
    4y2 + 27x3 = 0
  • d)
    4x3 + 27y2 = 0
Correct answer is option 'D'. Can you explain this answer?

Disha Nambiar answered  •  2 days ago
Explanation:

Differential Equation:
- Given differential equation: y = px + p^3
- We also know that p = dy/dx
- Substituting p = dy/dx in the given equation, we get y = x(dy/dx) + (dy/dx)^3

Solving the Differential Equation:
- To find the singular solution, we need to eliminate the arbitrary constant.
- To eliminate the arbitrary
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Fatigue strength for non-ferrous materials is defined at X stress cycles. The value of X is
  • a)
    103
  • b)
    105
  • c)
    107
  • d)
    109
Correct answer is option 'C'. Can you explain this answer?

Nayanika Yadav answered  •  2 days ago
Definition of Fatigue Strength:
Fatigue strength is the maximum stress that a material can withstand for a specified number of stress cycles before it fails due to fatigue.

Value of X for non-ferrous materials:
- For non-ferrous materials, the value of X for fatigue strength is typically defined at 10^7 stress cycles.
- This means that the material can withs
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Which one of the following pairs is not correctly matched?
  • a)
    Slenderness ratio : The ratio of length of the column to the least radius of gyration
  • b)
    Buckling factor : The ratio of maximum load to the permissible axial load on the column
  • c)
    Short column : A column for which slenderness ratio < 32
  • d)
    Strut : A member of a structure in any position and carrying an axial compressive load
Correct answer is option 'B'. Can you explain this answer?

Prateek Mukherjee answered  •  2 days ago
Explanation:

Incorrectly Matched Pair:

Buckling factor : The ratio of maximum load to the permissible axial load on the column
  • The buckling factor is not defined as the ratio of maximum load to the permissible axial load on the column.
  • The buckling factor is actually defined as the ratio of the critical load for buckling to the load a... more
  • It is used to determine the stability of a column under compressive loading.
  • An accurate buckling factor calculation helps in designing columns that can withstand buckling forces.



Correctly Matched Pairs:

Slenderness ratio : The ratio of length of the column to the least radius of gyration
  • The slenderness ratio is indeed defined as the ratio of the length of the column to the least radius of gyration.
  • It is used to determine the stability of a column under compressive loading.
  • A higher slenderness ratio indicates a higher risk of buckling.



Short column : A column for which slenderness ratio < />
  • A short column is typically defined as a column for which the slenderness ratio is less than 32.
  • Short columns are less prone to buckling compared to long columns.
  • They are more stable under compressive loading.



Strut : A member of a structure in any position and carrying an axial compressive load
  • A strut is indeed defined as a member of a structure in any position and carrying an axial compressive load.
  • Struts are commonly used in engineering and construction to support loads in compression.
  • They are designed to withstand compressive forces and prevent buckling.

When the body which is applied forces come in the stage of the limiting friction then the body over which this theorem is to be applied is termed as to come in ___________ equilibrium.
  • a)
    Unstable
  • b)
    Stable
  • c)
    Non-stable
  • d)
    Improper Stable
Correct answer is option 'A'. Can you explain this answer?

Prateek Mukherjee answered  •  2 days ago
Unstable Equilibrium
When a body is in a state of limiting friction, it means that the external forces applied are at the verge of overcoming the maximum static frictional force. At this point, the body is on the brink of motion but is still at rest due to the balancing of forces.

Explanation
- In this scenario, the body is said to be in unstable equilibrium beca
... more
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