GATE Previous years Thermodynamics questions Important Two-marks GATE questions By Rutuja Bothara

RUTUJA BOTHARA . Perusing B.Tech in Mechanical Engineering from Vellore Institute of Technology, Vellore.(2015-2019) Cleared JEE Mains 2015 Cleared VITEEE-2015 with AIR 8718 . Cracked HITSEEE-2015 with AIR 91 Worked as a Career Counsellor in Teachers Academy (2016- 2018) and BOLO app. https://unacademy.com/user/rurutujajb96-9511

A 100 W electric bulb was switched on in a 2.5 m x 3 m x 3 m size thermally insulated room having a temperature of 20 C. The room temperature at the end of 24 hours will be. (Take density of air 1.2 kg/m2 and C, of air 0.717 kJ/kg 321 341 0 450 C 470 C

During 24 hours heat liberated by bulb 'Q' is Q = 100 24 3600 = 8.64 10 Density of air = 1.2 kg/m3 Volume of room 2.5 x 3 x 3 22.5 m3 Mass of air 1.2 x 22.5 27 kg Let T2 is final temperature of gas Cv of air0.717 kJ/kg K Because volume of room is constant Q m Cv (T2-T1) 8.64 106 = 27 0.717 1000 (T2-20) T,-466.30 C 470 C

Nitrogen at an initial state of 10 bar, I m and 300K is expanded isothermally to a final volume of 2m. The p-v-T relation iRT, where a> 0 The final pressure. (A) will be slightly less than 5 bar B will be slightly more than 5 bar will be exactly 5 bar D) cannot be ascertained in the absence of the value of a

= constant. Vi2 P1-10 ba -a

A solar collector receiving solar radiation at the rate of 0.6 kW/m2 transforms it into the internal energy of a fluid at an overall efficiency of 50%. The fluid heated to 350 K is used to run a heat engine which rejects heat at 313 K. If the heat engine is to deliver 2.5 kW power, the minimum area (in sq. meters) of the solar collector required would be: -83.33 - 16.66 39.68 79.36

3So-313 He 313K So hea t recelued by heat engine 7.9 kW '. AreaTg 3G

During A Morse test on A 4-cylinder engine, the following measurements of brake power were taken at constant speed. All cylinders firing 3037 Kw.number 1 cylinder not firing 2102 KW .number 2 cylinder not firing 2102 KW, number 3 cylinder not firing 2100 KW number 4 cylinder not firing 2098 KW, the mechanical efficiency of the engine is eticency f the enginei, mechanical . 91.53% 85.07% 81.07% . 61.22%

when all cylinders are working Wheh cylindeE I is not 0rk hg P 2102 KW Powet Supplied by cy lih dee I P1 30 37 2102 9BS kW

Considering the relationship Tds-dU+pdV between the entropy (S), internal energy (U), pressure (p), temperature (T) and volume (V), which of the statement is correct. (A) It is applicable only for a reversible process (B) For an irreversible process TdS dU+pdV .(C) It is valid only for an ideal gas (D) It is equivalent to 1st law, for a reversible process

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RUTUJA Bothara

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Rajat singh

a year ago

gusious lecture

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