According to First law of thermodynamics,
Total internal energy of a system during a process remains constant
Total energy of a system remains constant
Workdone by a system is equal to the heat transferred by the system
Internal energy, enthalpy and entropy during a process remain constant
Correct Answer :
B. Total energy of a system remains constant
Related Questions
When a closely-coiled helical spring of mean diameter (D) is subjected to an axial load (W), the deflection of the spring (δ) is given by (where d = Diameter of spring wire, n = No. of turns of the spring, and C = Modulus of rigidity for the spring material)
WD3n/Cd⁴
2WD3n/Cd⁴
4WD3n/Cd⁴
8WD3n/Cd⁴
When a gas is heated at constant pressure
Its temperature will increase
Its volume will increase
Both temperature and volume will increase
Neither temperature not volume will increase
The area under the temperature-entropy curve (T - s curve) of any thermodynamic process represents
Heat absorbed
Heat rejected
Either (A) or (B)
None of these
The percentage reduction in area of a cast iron specimen during tensile test would be of the order of
More than 50 %
25-50 %
10-25 %
Negligible
Which of the following process can be made reversible with the help of a regenerator?
Constant pressure process
Constant volume process
Constant pvn process
All of these
The thickness of a thin cylindrical shell with hemispherical ends is __________ that of spherical ends.
Equal to
More than
Less than
None of these
A process, in which the temperature of the working substance remains constant during its expansion or compression, is called
Isothermal process
Hyperbolic process
Adiabatic process
Polytropic process
When a body is subjected to biaxial stress i.e. direct stresses (σx) and (σy) in two mutually perpendicular planes accompanied by a simple shear stress (τxy), then minimum normal stress is
(σx + σy)/2 + (1/2) × √[(σx - σy)² + 4 τ²xy]
(σx + σy)/2 - (1/2) × √[(σx - σy)² + 4 τ²xy]
(σx - σy)/2 + (1/2) × √[(σx + σy)² + 4 τ²xy]
(σx - σy)/2 - (1/2) × √[(σx + σy)² + 4 τ²xy]
A continuous beam is one which is
Fixed at both ends
Fixed at one end and free at the other end
Supported on more than two supports
Extending beyond the supports
Young's modulus is defined as the ratio of
Volumetric stress and volumetric strain
Lateral stress and lateral strain
Longitudinal stress and longitudinal strain
Shear stress to shear strain
A series of operations, which takes place in a certain order and restore the initial conditions at the end, is known as
Reversible cycle
Irreversible cycle
Thermodynamic cycle
None of these
The stress developed in a material at breaking point in extension is called
Breaking stress
Fracture stress
Yield point stress
Ultimate tensile stress
One kg of ethylene (C2H4) requires 2 kg of oxygen and produces 22/7 kg of carbon dioxide and __________ kg of water or steam.
9/7
11/7
7/4
1/4
The maximum diameter of the hole that can be punched from a plate of maximum shear stress 1/4th of its maximum crushing stress of punch, is equal to (where t = Thickness of the plate)
t
2t
4t
8t
The general gas equation is (where p = Pressure, v = Volume, m = mass, T = Absolute temperature, and R = Gas constant)
pv = mRT
pv = RTm
pvm = C
pv = (RT)m
The ratio of maximum shear stress developed in a rectangular beam and a circular beam of the same cross-sectional area is
2/3
3/4
1
9/8
The efficiency of the dual combustion cycle for the same compression ratio is __________ Diesel cycle.
Greater than
Less than
Equal to
None of these
The total energy of a molecule is shared equally by the various degrees of freedom possessed by it. This law is known as
Law of equipartition of energy
Law of conservation of energy
Law of degradation of energy
None of these
When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel, the process is known as __________ of fuel.
Atomisation
Carbonisation
Combustion
None of these
When cut-off ratio is __________ the efficiency of Diesel cycle approaches to Otto cycle efficiency.
Zero
1/5
4/5
1
Steam coal is a
Pulverised coal
Brown coal
Coking bituminous coal
Non-coking bituminous coal
Modulus of rigidity may be defined as the ratio of
Linear stress to lateral strain
Lateral strain to linear strain
Linear stress to linear strain
Shear stress to shear strain
The reading of the pressure gauge fitted on a vessel is 25 bar. The atmospheric pressure is 1.03 bar and the value of 'g' is 9.81 m/s2. The absolute pressure in the vessel is
23.97 bar
25 bar
26.03 bar
34.81 bar
The main cause for the irreversibility is
Mechanical and fluid friction
Unrestricted expansion
Heat transfer with a finite temperature difference
All of the above
For the beam shown in the below figure, the shear force diagram between A and B is
A horizontal line
A vertical line
An inclined line
A parabolic curve
The efficiency of Diesel cycle approaches to Otto cycle efficiency when
Cut-off is increased
Cut-off is decreased
Cut-off is zero
Cut-off is constant
A composite shaft consisting of two stepped portions having spring constants K₁ and K₂ is held between two rigid supports at the ends. Its equivalent spring constant is
K₁ K₂
(K₁ + K₂)/ 2
(K₁ + K₂)/ K₁ K₂
K₁ K₂/ (K₁ + K₂)
The shear force diagram for a simply supported beam carrying a uniformly distributed load of w per unit length, consists of
One right angled triangle
Two right angled triangles
One equilateral triangle
Two equilateral triangles
An open system is one in which
Heat and work crosses the boundary of the system, but the mass of the working substance does not crosses the boundary of the system
Mass of the working substance crosses the boundary of the system but the heat and work does not crosses the boundary of the system
Both the heat and work as well as mass of the working substance crosses the boundary of the system
Neither the heat and work nor the mass of the working substance crosses the boundary of the system
The pull required to crush the rivet per pitch length is
p.t.σt
d.t.σc
π/4 × d² × σt
π/4 × d² × σc