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BARC 2020: Mini Mock 1

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Question 1

A strip having thickness 30 mm is to be rolled to a thickness of 15 mm using rolls mills of diameter 300 mm. For unaided bite, the coefficient of friction should be nearly :

Question 2

Which of the following are causes of irreversibility?

1) Thermodynamic Equilibrium

2) Friction

3) Fluid Viscosity

4) Vapour Pressure

Question 3

The open circuit voltage and short circuit current for a welding operation are given as 70V and 200A . For the condition of max power what should be the setting of voltage and current

Question 4

A petrol engine working on Otto cycle with efficiency 48% and clearance volume is 30 cm3. Find the stroke length, if the engine is square. (γ = 1.4)

Question 5

A reversible heat engine (E) operates using three thermal reservoirs with temperatures as shown in the following figure. If , the efficiency of the engine is :

Question 6

A welding operation is done with voltage and current of 60 V and 100 A.The cross section of the weld is 150 mm2. And the specific energy for thus welding operation is 5.2 J/mm3. The welding speed is 6 mm/s. the supply efficiency is 90%, Find the melting efficiency in %.

Question 7

For a steady flow process in a turbine from state 1 to state 2, h1= 450 kJ/kg, h2= 150 kJ/kg and entropy changes from s= 1.2 kJ/kgK to s= 0.8 kJ/kgK. Ambient temperature is 300 K. Find the change in availability (kJ) _________.

Question 8

The major difficulty during welding of aluminum is due to its

Question 9

An ideal gas is flowing through an insulated pipe at the rate of 4 kg/s. If there is a 15% pressure drop due to friction from inlet to exit of pipe then the rate of exergy loss is ( take R =0.287 kJ/kgK, and atmospheric temperature 27 )

Question 10

A gas from a rigid bottle of compressed inert gas is used to inflate a balloon, originally folded completely flat to a 0.8 m3. The work interaction (in kJ) is (assume the pressure in balloon is atmospheric at all times)

Question 11

Two finite heat source (identical) are present at temperatures 1600 K and 400 K respectively. If the maximum work output is required by having an reversible engine in between them. Then what is the final temperature of both the sources?

Question 12

Design a side cylindrical riser to feed a cubical casting of 20 cm side. Taking shrinkage of material as 6%, then radius of the riser is ___________mm (consider riser volume to be at least 3 times the shrinkage volume)

Question 13

A cyclic device operates between three thermal reservoirs, as shown in the figure. Interactions between the cyclic device and the respective thermal reservoirs  are shown in the figure and  all are in the form of heat transfer. The cyclic device can be _____.

Question 14

An ideal gas of mass 0.5 kg has a pressure of 600 kPa, a temperature of 77 and a volume of 0.08 m3. This gas undergoes an irreversible process to a final pressure of 600 kPa and final volume of 0.12 m3, during which the heat addition and work done on gas are 2 kJ and 30 kJ respectively. The value of Cv of gas is

Question 15

In a rolling operation using rolls of diameter 500 mm, if a 25 mm thick plate cannot be reduced to less than 20 mm in one Pass, the coefficient of friction between the roll and the plate is ___________

Question 16

A cube shaped casting solidifies in 5 min. The solidification time for a cube of the same material, which is 8 times lighter than the original casting will be ________ minutes.

Question 17

A 20 mm, HSS drill bit with a point angle of 118 is to drill a through hole on a metallic plate of thickness 100mm with a cutting speed of 333.33 mm/s and a feed value of 0.22 mm/rev. If the drill is touching the surface of the plate at start, the drilling time in s, is nearest to :

Question 18

The weight placed on the steam exhaust port of a domestic pressure cooker never allows the pressure to build up above 250 KPa inside the cooker. The latent heat of vaporization of water is 2257 kJ/Kg at 100 °C and 101.325 KPa. The temperature ( °C) at which water boils in the cooker is

Question 19

Two bodies A and B of heat capacities CA and CB at temperatures TA and TB are brought to the same temperature T by means of a reversible heat engine then, the correct expression for is given by

Question 20

The steam is expanded isentropically in steam turbine from 20 bar, 350°C to 0.08 bar and then it condensed to saturated liquid water in condenser. The pump feeds back the water into boiler. Neglect losses in the processes, the cycle efficiency (in percentage) is
Given data: At P = 0.08 bar, hfg = 2403.1 kJ/kg, sfg = 7.6361 kJ/kg K, vf = 0.001008 m3/kg
h1 =3159.3 kJ/kg, s1 = 6.9917 kJ/kg K, h3 = 173.88 kJ/kg, s3 = 0.5926 kJ/kgK,
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