Only rocket engines can be propelled to space because
ISRO Scientist or Engineer Mechanical 2007
For the following questions answer them individually
The universal gas constant of a gas is the product of molecular weight of the gas and
Vander Waal’s equation of state of a gas is
The radiative heat transfer rate per unit area (W/m$$^2$$) between two plane parallel grey surfaces (emissivity = 0.9) maintained at 400 K and 300 K is (Stefan Bottzman constant
$$\sigma = 5.67 \times 10^{-8} W/m^2 K^4$$)
The efficiency $$\eta$$ of any heat engine and efficiency $$\eta_R$$ of a reversible heat engine operating between common heat source and heat sink are related as
A spherical shaped vessel of 1.4 m outer diameter is 90 mm thick. Find the rate of heat leakage, if the temperature difference between the inner and outer surfaces is $$220^\circ C$$. Thermal conductivity of the material of the sphere is 0.083 W/m K.
The velocity componentsin the x and y directions are given by $$u = \lambda xy^3 - x^2y; v = xy^2 - \frac{3}{4}y^4$$ The value of $$\lambda$$ for a possible flow field involving an incompressible fluid is
The temperature field in a body varies according to the equation $$T(x, y) = x^3 + 4xy$$. The direction cf fastest variation in temperature at the point (1, 0) is given by
The temperature distribution at a certain input of time in concrete slab during curing is given by $$T = 3x^2 + 3x + 16$$ where x is in cm and T is in K. The rate of change of temperature with time is given ($$\alpha = 0.0003 cm^2/sec$$)
300 kJ/sec of heat is applied at a constant fixed temperature of $$290^\circ C$$ to a heat engine. The heat rejection takes place at $$8.5^\circ C$$. then match the following:
If the governing equation fora flow field is given by $$\triangledown^2\phi = 0$$ and the velocity is given by
With rise in temperature thermal conductivity of air
In a reversible adiabatic process, the ratio of $$\frac{T_1}{T_2}$$ is equal to
Chances of occurrenceof cavitation are high if the
The general equation of continuity for three-dimensional flow of a incompressible fluid for steady flow is
A liquid compressedin cylinder has a volume of 0.04 m$$^3$$ at 50 kg/cm$$^2$$ and a volume of 0.039 m$$^3$$ at 150 kg/cm$$^2$$. The bulk modulus of liquid is
The buoyancy depends on
A fluid jet discharging from a 100 mm diameter orifice has a diameter of 80 mmat its vena contracta. The coefficient of contraction is
If a jet of water of area ‘A’ strikes with velocity ‘V’ a series of flat plates mounted on a wheel of mean diameter D rotating at N rpm, then force exerted will be equal to
The maximum height of a siphon for a fluid of specific gravity $$\rho$$ under atmospheric conditions is
A centrifugal pump with peripheral speed ‘V’ was selected fora total lift of 100 m. Actually pump wasto be operated fora total lift of 400 m. The peripheral speed should actually be (other conditions remaining same)
The specific speed of pump and turbine respectively are given as
Match List I with List II and select the correct answer
Given that
$$\alpha_1$$ = nozzle angle
n = number of rows of moving blades, in a velocity compounded impulse turbine, the optimum blade speedratio is
The following terms relate to floating bodies:
Centre of gravity ... G, MetaCentre ... M, Weight of floating body ... W, Buoyant force ... Fg, Match List I with List II and select the correct answer
A pipeline connecting two reservoirs has its diameter reduced by 20% due to deposition of chemicals. For a given head difference in the reservoirs with unaltered friction factor, this would cause a reduction in discharge of
An open rectangular box of base 2m $$\times$$ 2m contains a liquid of specific gravity 0.80 up to a height of 2.5 m. If the box is imparted vertically upward acceleration of 4.9m/s$$^2$$, what will be the pressure on the base of the tank?
The tank shown in the figure below is closed at top and contains air at a pressure of $$P_A$$. The value of $$P_A$$, for the manometer readings shown will be
$$P = 2i - 3j, Q = -3i + 4j - 2k$$, and R are in equilibrium, if R is
A rigid body is rotating with constant angular velocity $$\omega$$ about a fixed axis, if v is the velocity of a point of the body, then curl v =
Laplace transform of $$\sin^3 2t$$ is
The value of the determinant
is
Solution of $$(D^2 + 4)y = \sin^2 x$$, is
The value of k for which the lines $$2x + y - 1 = 0, 4x + 3y - 3 = 0$$ and $$3x + ky - 2 = 0$$, are concurrent is
A box contains 5 black and 5 red balls. Two balls are randomly picked one after another from the box, without replacement. The probability for both balls being red is
$$x^3 + x \sin x$$ Is a ............ function
$$\int \frac{dx}{x\sqrt{x^2 - a^2}}$$ is
Eigen values of $$\begin{bmatrix}-5 & 2 \\2 & -2 \end{bmatrix}$$ are
Hardness of martensite is about
Which is false statement about annealing. Annealing is done to
Materials exhibiting time bound behavior are known as
Shrinkage allowance is made by
Machinablity depends on
Spinning operation is carried out on
Acceptance sampling is widely used in
Gratings are used in connection with
Which of the following errors are inevitable in the measuring system and it would be vainflul exercise to avoid them
A block whose massis 650 gm is fastened to a spring of spring constant K equals 65 N/m whose other end is fixed. The block is pulled a distance x = 11 cm from its equilibrium position at x = 0 on a smooth surface, and released from rest at t= 0. The maximum speed‘S’ of the oscillating block is
A block of mass‘m’is connected to two springs of stiffness $$K_1$$ and $$K_2$$ as shown in the figure $$f_1$$ and $$f_2$$ are the frequencies of the block when connected to $$K_1$$ and $$K_2$$ independently. Then the frequency of ‘m’ when connected to $$K_1$$ and $$K_2$$ as in the figure is
The block has a kinetic energy of 3J and the spring connecting the block has an elastic energy of 2J (shown in figure). When the block is at x = +2.0 cm. What is the kinetic energy when the block is at x = 0.
Fora body subjected to direct stresses $$\sigma x, \sigma y$$ and $$\sigma z$$ the direct strain $$ε_x$$ in x direction is (where E and $$\gamma$$ are Young’s Modulus and Poisson’s ratio respectively)
A circular shaft subjected to torsion undergoesa twist of $$1^\circ$$ in a length of 120 cm. If the maximum shear stress inducedis limited to 1000kg/cm$$^2$$ and if modulus of rigidity $$G = 0.8 * 10^6 Kg/cm^2$$, then the radius of the shaft should be
A hollow shaft of same cross-section area as solid shaft transmits
The extension of a mild steel bar 4m long, 2000 mm$$^2$$ cross section under the action of an axial load of 20kN, if E = 2(10$$^5$$) N/mm$$^2$$, is
InIsection shear load is resisted mainly by
Shear force is
Maximum shear stress in Mohr’s circle is equal to
If a material expands freely dueto heating it will develop
When acolumn is fixed at both ends, corresponding Euler’s critical load is
A metal pipe of 1 m diameter contains a fluid having a pressure of 10 kgf/cm$$^2$$. If the permissible tensile stress in the metal is 200 kgf/cm$$^2$$, then the thickness of the metal required for making the pipe would be
Circumferential and longitudinal strains in the cylindrical boiler under internal steam pressure are $$ε_1$$ and $$ε_2$$ respectively. Change in the volume of the boiler cylinder per unit volume will be
lf water in closed pipe freezes, the pipe will
The notch angle of Izod impact test specimenis
Which of the following statements regarding laws governing the friction between dry surfacesare correct?
1. The friction force is dependenton the velocity sliding.
2. The friction force is directly proportional to the normal force.
3. The friction force is dependent on the materials of the contact surfaces.
4. The friction force is independent of the area of contact.
Select the correct answer using the codes given below:
A simple spring-massvibrating system has a natural frequencyof N. If the spring stiffness is halved and the massis doubled, then the natural frequency will become
Under logarithmic decrement, the amplitude of successive vibrations are
Periodic time of simple pendulum is given by
In a single reduction,a large velocity ratio is required. The best transmission is
Idler pulley is used
If two bodies one light and other heavy have equal kinetic energies, which onehas a greater momentum
A heavy block of mass m is slowly placed on a conveyer belt moving with speedv.If coefficient of friction between block and the belt is $$\mu$$, the plock will slide on the pert through distance
A car moving with uniform acceleration covers 450 m in a 5 second interval, and covers 700 m in the next 5 second interval. The acceleration of the car is
A particle starts with a velocity 2m/sec and movesona straight-line track with retardation 0.1 m/sec$$^2$$. The time at which the particle is 15 m from the starting point would be
Two particles with massesin the ratio 1 : 4 are moving with equal kinetic energies. The magnitudeof their linear momentums will conform to the ratio
A stone is projected horizontally from a cliff at 10 m/sec and lands on the ground belowat 20 m, from the baseofthe cliff. Find the height of the cliff. Use g = 10 m/sec$$^2$$ ?
Oscillation of a particle is prescribed by the equation $$x = 3 \cos 0.25 \pi t$$ Wheret is the time in seconds.
Then time taken by the particle to move from position of equilibrium to maximum displacement is
Which of the following is not a scalar quantity
Which of the following stresses are associated with the tightening of a nut on a stud?
1. Tensile stresses due to stretching of stud.
2. Bending stresses of stud.
3. Transverse shear stresses acrossthreads. .
4. Torsional shear stresses in threads due tofrictional resistance.
Select the correct answer using the codes given below Codes:
A thin copper wire at $$300^\circ$$ is suddenly immersed in water at $$30^\circ C$$. It cools down to $$150^\circ C$$ in 70 seconds. It is then reheated to the initial temperature of $$300^\circ C$$ and suddenly exposedto air at $$30^\circ C$$ where it cools downto $$150^\circ C$$ in 200 seconds. This difference in cooling time is due to
The heat flow rate through parallel walls of thickness $$L_1, L_2$$ and $$L_3$$, having surface areas $$A_1, A_2$$ and $$A_3$$, thermal conductivities $$k_1, k_2$$ and $$k_3$$,
respectively, with the first and last walls maintained at temperatures $$t_1$$ and $$t_2$$ will be
