Starting from the same initial conditions, an ideal gas expands from volume $$V_1$$, to $$V_2$$, in three different ways, the work done by the gas is $$W_1$$, if the process is purely isothermal, $$W_2$$, if purely isobaric and $$W_3$$, if purely adiabatic, then
ISRO Scientist or Engineer Mechanical 2016
For the following questions answer them individually
A beaker filled with hot water in a room cools from $$70^\circ C$$ to $$65^\circ C$$ in $$t_1$$ minutes, $$65^\circ C$$ to $$60^\circ C$$ in $$t_2$$ minutes and from $$60^\circ C$$ to $$55^\circ C$$ in $$t_3$$ minutes. Then,
A house refrigerator with its door open is switched on in a closed room. Theair in the room is
An elevator has a mass of 5000 kg. When thetension in the supporting cable is 60 kN, the acceleration of the elevator is nearly
The piston of a steam engine moves with simple harmonic motion. The speed of rotation of crank is 120 rpm with a stroke of 2m. Whatis the velocity of piston whenit is 0.5 m from
the centre?
The sine of the angle between the two vectors $$a = 3i + j + k$$ and $$b = 2i - 2j + k$$ is
Equation of the line normal to function $$f(x) = (x - 8)^{\frac{2}{3}} + 1$$ at P(0, 5) is
There are 20 locks and 20 matching keys. Maximum number of trials required to match all the locks is
If $$\phi(x, y, z)$$ is a scalar function and $$\triangledown^2 f = 0$$, then $$\phi$$ is
A and B are two candidates appearing for an interview by a company. The probability that A is selected is 0.5 and the probability that both A and B are selected is at most 0.3. The probability of B getting selected is
The reading ofa spring balance is from 0 to 200 N and is 10 cm long. A body suspended from the spring balance is observed to oscillate vertically at 2 Hz. The mass of the body is nearly
A ball is dropped vertically from a height d above the ground. It hits the ground and bounces up to a height d/2. Neglecting the subsequent motion and air resistance, its velocity (v) varies with height (h) above the ground as
A 10 kW drilling machineis used to drill a bore in a small aluminium block of mass 8 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the block? (specific-heat of aluminum : 0.91 J/($$g^\circ C$$))
In the figure shown, the minimum ratio of $$\frac{\mu_1}{\mu_2}$$ so that the masses move together with the application of force F is
A thin wire of length L and uniform linear mass density $$\rho$$ is bent into a circular loop with centre O as shown in figure. The moment of inertia of the loop about the axis 'XX' is
A 10 kg mass is hung from 2 light, inextensible strings as shown. The tension in the horizontal string is nearly
A block of ice at $$-10^\circ C$$ is slowly heated and converted to steam at $$100^\circ C$$. Which of the following curves represent the phenomena qualitatively?
If the temperature of the sun is doubled, the rate of energy received on earth will be increasedby a factor of
The transmission of heat by molecular collision is called
If two ends of rods of length L and radius r, made of same material are kept at the same temperature difference, which of the following rods conduct most heat per unit time?
A thermometer works on the principle of
The working temperatures in evaporator and condensercoils of a refrigerator are $$-25^\circ C$$ and $$30^\circ C$$, respectively. The COP of the refrigerator is 0.85 of the maximum COP for a power input of 2 kW. The refrigeration effect produced will be
A mercury thermometer was first placed in melting ice and the length of mercury column was observed to be 10 mm; when it was placed in steam, the length of the column was
250 mm. Whenplaced in tap water, the length of the column was 58 mm. The temperature of the tap water is
The amountof steam (at $$100^\circ C$$) required to raise the temperature of 200 g of water from $$60^\circ C$$ to $$100^\circ C$$ is
A engine works on Carnot cycle between $$727^\circ C$$ and $$227^\circ C$$. The efficiency of the engine is
A steam thermal powerplant works on
A boat which has a speed of 5 km/h in still water crosses a river of width 1 km along the shortest path in 15 min. The velocity of the river in km/h is
In 1s, a particle goes from point A to point B, moving in a semicircle (as shown in figure). The magnitude of the average velocity is
A block is made to slide down an inclined plane ($$30^\circ$$ with horizontal) which is smooth. It starts sliding from rest and takes a time ‘t’ to reach the bottom of the plane. An identical bodyis freely dropped from the same point. The time the body takes to reach the bottom is
What parameterwill remain constant in a throttling process?
The main objective of ‘shot peening’ is to improve which property of metal parts
When a material is strain hardened?
Which thread is more suited in powerscrew to take load on both directions?
A holeis specified as $$\phi 50^{\left(\frac{+0.050}{-0.000}\right)}$$ mm. The mating shaft has a clearance fit with minimum clearance of 0.02 mm. The tolerance on the shaft is 0.03 mm. Maximum clearance between hole and shaft is
In a cutting operation the cutting speed was reduced by 20%. Assuming n = 0.5 and C = 350 in Taylor’s equation, the increasein toollife is
Mass production of seamless tubes is by the process of
Misrunis a casting defect which occurs due to
A simple steam powercycle receives 100,000 kJ/min as heat transfer from hot combustion gases and rejects 66,000 kJ/min as heat transfer to the environment. If the pump power
required is 1400 kJ/min, the thermal efficiency of the cycle and turbine power output is
Air at 100 kPa, $$2^\circ C$$ occupies a 10 liter piston-cylinder device that is arranged to maintain constant air pressure. This device is now heated until its volume is 20 liters. The work produced by the air is
A heat engine working with a thermal efficiency of 35% receives 2 kW of heat from a furnace. The waste heat rejected from the engine is
Joule-Thompsoncoefficient for an ideal gas is
Air is heated from $$0^\circ C$$ to $$100^\circ C$$ in a sealed metal container. Its density
If a certain massof moist air in an air tight vessel is heated to a higher temperature, then
Air is accelerated isentropically from 100 m/s to 300 m/s in a nozzle. If the temperature at the inlet is $$127^\circ C$$, the inlet Mach number is (take R = 287J/(kg K) and specific heat ratio = 1.4)
Two equal forces are acting at a point with an angle of $$60^\circ$$ between them. If the resultant force is equal to $$60 \sqrt{3}$$ , what is the magnitudeof each force?
Atwo member truss ABCis configured as shown in figure. The force in the member AB is
Four forces of magnitudes 20 N, 40 N, 60 N and 80 are acting respectively along the four sides of a square ABCD as shown in figure. The magnitude of resultant is
In a simply supported beam loaded as shown in figure, the maximum bending moment in Nm is
Two steel rails each of 12 m length are laid with a gap of 1.5 mm at ends at a temperature of 24°C. The thermal stress produced at a temperature of $$40^\circ C$$ is (take $$E = 2 \times 10^5$$ N/mm$$^2$$ coefficient of thermal expansion = $$12 \times 10^{-6}/^\circ C$$)
An aluminum tensile test specimen has a diameter, $$d_o = 25 mm$$ and a gauge length of $$L_o = 250 mm$$. If a force of 175 KN elongates the gauge length by 1.25 mm, the modulus
of elasticity of the material is nearly
A tubular shaft, having an inner diameter of 30 mm and an outer diameter of 40 mm, is to be used to transmit 80 kW of power. The speed ofrotation of the shaft so that the shear
stress will not exceed 50 MPa is
A cantilever beam oflength L is subjected to a concentrated load P at a distance of L/3 from the free end. The deflection at the free end is
What is the common surface hardening treatment in steel?
Which of the following order of crystal structure will match with metals Iron — Copper — Zinc in that order?
A resistance spot-welding operation is performed on twopieces of 1.5 mm thick sheet steel using 12000 amps current for a duration of 0.20 second. The electrodes are 6 mm in
diameter at the contacting surfaces. Resistance is assumed to be 0.0001 ohms and the resulting weld nugget is 6 mm in diameter and 2.5 mm thick. The unit melting energy for the metal is 12 J/mm$$^3$$. What portion of heat generated was used to form the weld?
A manometer is used to measure the pressure of a gas in a tank. The fluid used has a specific gravity of 0.85 and the manometer column height is 55 cm, as shown in figure. If the local atmospheric pressure is 96 kPa, what is the absolute pressure in the tank?
A crane is used to lower weights into the sea (sea water density = 1025 kg/m$$^3$$) for an underwater construction project. What is the percentage reduction in the tension
in the rope of the crane due to a rectangular 0.4 m $$\times$$ 0.4 m $$\times$$ 3 m concrete block (density = 2300kg/m*) when it is completely immersed in water compared to the tension in
the rope when it was suspendedin air
A steady, incompressible, two-dimensional velocity field is given by,
$$\vec{V} = (u, v) = (0.5 + 0.8 x)\vec{i}+(1.5 + 0.8 y)\vec{j}$$
The number of stagnation points there in the flow field is
A piezometer and a Pitot tube are tapped into a horizontal water pipe, as shown in figure. The velocity of water at the center of the pipe is
The pressure difference between the inside and outside of a liquid droplet of diameter 'd' due to surface tension ($$\sigma$$) is given by the relation
A stream function is given by $$\psi = 4x - 3y$$. The resultant velocity at any point is
The coefficient of discharge for an orifice meteris in the range
The hydraulic diameter, $$D_h$$, of a rectangular duct with sides 'a’ and 'b' is
A flat plate of length 1 m and width 50 cm is placed in an air stream at $$30^\circ C$$ blowing parallel to it. The convective heat transfer co-efficient is 30 W/(m$$^2$$K). The heat transfer if the plate is maintained at a temperature of $$400^\circ C$$ is
It is required to insulate a kitchen oven with cork board (K = 0.043 W/(m K)) so that the heat losses from the oven does not exceed 400 W/m$$^2$$ when the inner surface of the oven is at $$225^\circ C$$ and the outer surface of the oven is at $$40^\circ C$$. The thickness of insulation required is nearly
A radiator in a domestic heating system operates at a surface temperature of $$55^\circ C$$. Assuming the radiator behaves as a black body, the rate at which it emits the radiant heat per unit area is (assume $$\sigma = 5.67 \times 10^{-8} W/(m^2 K^4)$$)
Agrey body is defined such that
Monochromatic emissivity of the body is dependent of wave length
Asystem is undergoing a cycle that consists of three processes. During the first process, the work is 5 kJ and the heat is 23 kJ. In the second process no work takes place and the heat interaction is -50 kJ. The third process is adiabatic. The workin the third process is
Multi stage centrifugal pumpsare used for
A wire has a mass ($$0.3 \pm 0.003$$) g, radius ($$0.5 \pm 0.005$$) mm and length ($$6 \pm 0.06$$) cm. The maximum percentage error in the measurementof density is
Match the items in column-1 and column-2 and choose the correct combination
Which ofthe following pressure gauge is generally used for the calibration of other pressure measuring gauges
In a ball bearing, if the number of balls is reduced to half and diameter of the ball is increased to 4 times, then static load capacity of the ball bearing is
The velocity of sound in winter compared to summer will be
Gaseous Nitrogen at $$30^\circ C$$ is expanded through a converging nozzle from a total pressure of 0.5 MPa to a back pressure chamber.If the back pressure is increased from 0.1 MPa to 0.4 MPa in steps of 0.02 MPa, the trend in massflow rate through the nozzle
What is the value of
Critical to Stagnation Pressure ratio $$\left(\frac{P^*}{P_0}\right)$$ for an expansion process is
Match the items in column-1 and column-2 and choose the correct combination
A Pelton wheel turbine operates under a head of 125 m at a speed of 2000 rpm. To operate very close to the maximumefficiency, the mean diameter of the Pelton wheelis nearly
