A bar of copper and steel form a composite system, which is heated to a temperature of 40°C. The stress induced in the copper bar will be
Tensile
Compressive
Shear
Zero
Correct Answer :
B. Compressive
Related Questions
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
The buckling load for a given column depends upon
Area of cross-section of the column
Length and least radius of gyration of the column
Modulus of elasticity for the material of the column
All of the above
Steam coal is a
Pulverised coal
Brown coal
Coking bituminous coal
Non-coking bituminous coal
If in the equation pvn = C, the value of n = ∝, then the process is called
Constant volume process
Adiabatic process
Constant pressure process
Isothermal process
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 maximum stress produced in a bar of tapering section is at
Smaller end
Larger end
Middle
Anywhere
The compression ratio for Diesel engines is
3 to 6
5 to 8
15 to 20
20 to 30
For a beam, as shown in the below figure, when the load W is applied in the centre of the beam, the maximum deflection is
Wl3 / 48EI
5Wl3 / 384EI
Wl3 / 392EI
Wl3 / 384EI
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
Which of the following is correct?
Absolute pressure = Gauge pressure + Atmospheric pressure
Gauge pressure = Absolute pressure + Atmospheric pressure
Atmospheric pressure = Absolute pressure + Gauge pressure
Absolute pressure = Gauge pressure - Atmospheric pressure
Which of the following statement is correct?
The increase in entropy is obtained from a given quantity of heat at a low temperature.
The change in entropy may be regarded as a measure of the rate of the availability or unavailability of heat for transformation into work.
The entropy represents the maximum amount of work obtainable per degree drop in temperature.
All of the above
Modulus of rigidity is defined as the ratio of
Longitudinal stress to longitudinal strain
Volumetric stress to volumetric strain
Lateral stress to Lateral strain
Shear stress to shear strain
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
If percentage reduction in area of a certain specimen made of material 'A' under tensile test is 60% and the percentage reduction in area of a specimen with same dimensions made of material 'B' is 40%, then
The material A is more ductile than material B
The material B is more ductile than material A
The ductility of material A and B is equal
The material A is brittle and material B is ductile
When a body is subjected to three mutually perpendicular stresses, of equal intensity, the ratio of direct stress to the corresponding volumetric strain is known as
Young's modulus
Modulus of rigidity
Bulk modulus
Poisson's ratio
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 maximum 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]
The ratio of the largest load in a test to the original cross-sectional area of the test piece is called
Elastic limit
Yield stress
Ultimate stress
Breaking stress
The property of a working substance which increases or decreases as the heat is supplied or removed in a reversible manner, is known as
Enthalpy
Internal energy
Entropy
External energy
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
During a tensile test on a specimen of 1 cm cross-section, maximum load observed was 8 tonnes and area of cross-section at neck was 0.5 cm². Ultimate tensile strength of specimen is
4 tonnes/ cm²
8 tonnes/ cm²
16 tonnes/ cm²
22 tonnes/ cm²
The natural petroleum may be separated into
Petrol
Kerosene
Fuel oil
Lubricating oil
A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as
Carnot cycle
Stirling cycle
Otto cycle
Diesel cycle
The efficiency of Stirling cycle is __________ Carnot cycle.
Greater than
Less than
Equal to
None of these
An open cycle gas turbine works on
Carnot cycle
Otto cycle
Joule's cycle
Stirling cycle
The behaviour of a perfect gas, undergoing any change in the variables which control physical properties, is governed by
Boyle's law
Charles' law
Gay-Lussac law
All of these
The thermal efficiency of an ideal gas turbine plant is given by (where r = Pressure ratio)
rγ - 1
1 - rγ - 1
1 - (1/r) γ/γ - 1
1 - (1/r) γ - 1/ γ
According to Kelvin-Planck's statement of second law of thermodynamics,
It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body
None of the above
A column is said to be a short column, when
Its length is very small
Its cross-sectional area is small
The ratio of its length to the least radius of gyration is less than 80
The ratio of its length to the least radius of gyration is more than 80
Carbonisation of coal consists of
Drying and crushing the coal to a fine powder
Moulding the finely ground coal under pressure with or without a binding material
Heating the wood with a limited supply of air to temperature not less than 280°C
None of the above
In a tensile test on mild steel specimen, the breaking stress as compared to ultimate tensile stress is
More
Less
Same
More/less depending on composition