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GATE 2020: Toppers Quiz 7 (App update required to attempt this test)

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Question 1

Which of the following statement are the valid consequences of First law of Thermodynamics.
1) Heat transfer is a path function
2) Energy of an isolated system is always constant.
3) Perpetual Motion Machine of 1st kind is not possible.

Question 2

For a shaft transmitting torque, the equivalent twisting moment is 20 kN-m and equivalent bending moment is 14 kN-m. If the allowable stresses in shear and bending are 50 MPa and 100 MPa respectively, then the minimum diameter of the shaft is ___ mm.

Question 3

Two horizontal steam pipes having diameter of 120mm and 300mm are so laid in the boiler house that the mutual heat transfer may be neglected. The surface temperature of pipe is 470°C. If the temperature of the ambient air is 30°C. Calculate ratio of heat loss per metre length of pipes. Use: Nu= C(

Question 4

For a lawn sprinkler, diameter of both the nozzle is 1cm and Va = Vb = 10 m/s( where V is the velocity of water in static position at A and B.. What is the angular velocity of sprinkler?

Question 5

Air enters a counter-flow heat exchanger at 70 °C and leaves at 40 °C. Water enters at 30 °C and eaves at 50 °C. The LMTD in deg. C is

Question 6

A long column is most likely to fail by __________.

Question 7

Two long parallel surfaces each of emissivity 0.6 are maintained at 227°C and 1227°C respectively. If a polished aluminium shield (emissivity = 0.05) is placed between them, then find the shield temperature (in °C) under the steady state conditions.

Question 8

There are two blocks connected by a light string placed on the inclined parts of a triangular structure as shown in the figure. The coefficients of static friction is 0.3 at each of the surfaces. The minimum value of ‘M’ for which the system remains at rest is ___ kg.

Question 9

In a saloon customers arrive at the rate of 4 per hour and the time taken to serve a customer is 10 minutes. What is the waiting time of a customer before he is being served.

Question 10

An adiabatic turbine receives a gas at 5 bar and 1000 °C and discharges at 1.2 bar and 670 °C.The second law efficiency (in percentage ) of the turbine is ____. 
(cp= 1.09 kJ/kgK, cv= 0.815 kJ/kgK and neglect any change in kinetic and potential energy).
Take, To= 300K
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