Download 95HE-4

95HE-4
Sr. No. 5
EXAMINATION OF MARINE ENGINEER OFFICER
Function: Marine Engineering at Operational Level
HEAT ENGINES
INDIA (2001)
CLASS IV
(Time allowed - 3 hours)
Afternoon Paper
Total Marks 100
N.B. - (1) All questions are compulsory.
(2) All questions carry equal marks.
(3) Neatness in handwriting and clarity in expression carries weightage
1. The high thermal conductivity of metal is due to free electrons. The relevant electron property is
A. it being charged
B. its high average energy
C. its high average thermal speed
D. its low volume
2. Water can be heated in a cup of paper because
A. Paper is a good conductor of heat
B. Paper has high specific heat
C. Paper is thin
D. Paper is good radiator of heat
3. Which of the following combinations of properties would be most desirable for a cooking pot
A. High specific heat and low thermal conductivity
B. Low specific heat and high thermal condcutivity
C. High specific heat and high thermal conductivity
D. Low specific heat and low thermal conductivity
4. If equal quantities of ice melts completely in two identical containers in 30 and 20 minutes
respectively, the termal conductivities of the material of the two containers are in the ratio
A. 1 : 1
B. 1 : 2
C. 3 : 2
D. 2 : 3
5. At what temperature is the root mean square velocity of gaseous hydrogen molecules equal to that of
oxygen molecules at 470C ?
A.
B.
C.
D.
200K
800K
- 730K
30K
6. A gas at a pressure P0 is contained in a vessel . If the masses of all the molecules are halved and their
velocities doubled, the resulting pressure P would be equal to
A. 4 P0
B. 2 P0
C. P0
D. P0 / 2
7. A length of steel wire 2.5mm diameter is heated from 13OC to 113OC and its ends are securely
fastened while the wire is hot. Find the stress in the wire when it cools down to its original
temperature, assuming the elastic limit of the wire is not exceeded.
Take the coefficient of linear expansion of the steel as 1.2  10-5/OC and the modulus of elasticity as
207  109 N/m2.
8. An air reservoir contains 20kg of air at 3300kN/m2 and 16OC. The air is heated at constant volume to
350C. Calculate the final pressure and heat energy transfer. Take R for air = 0.287 kJ/kg K, specific
heat at constant volume C = 0.718 kJ/kg K, the atmospheric pressure = 100 kN/m2.
Note: Neglect any expansion of the reservoir.
9. Derive from the fundamentals the characteristics equation of a perfect gas pV = mRT.
A vessel of volume 0.65m3 contains air at 27.6 bar at 17OC. Calculate the final pressure after 3.5kg of
air is added if the final temperature is 20.5OC. Take R for air = 0.287 kJ/kg K.
10. Prove that in a single stage ideal reciprocating air compressor, when the gas is compressed
adiabatically - Work done per cycle = n p1V1 [(p2/p1)n-1/n – 1] Neglect clearance volume.
n-1
1.146kg of air at a pressure of 1 bar and 25OC is compressed to 13 bar, Calculate the work done per
cubic meter of air taken in the cylinder when the air is compressed adiabatically. Take 1 bar =
100kN/m2, n = 1.4.
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95HE-4
Sr. No. 5
EXAMINATION OF MARINE ENGINEER OFFICER
Function: Marine Engineering at Operational Level
HEAT ENGINES
CLASS IV
(Time allowed - 3 hours)
Afternoon Paper
INDIA (2001)
Total Marks 100
N.B. - (1) All questions are compulsory.
(2) All questions carry equal marks.
(3) Neatness in handwriting and clarity in expression carries weightage
Answers
Answer for Question No. 1
Correct Answer : C
Answer for Question No. 2
Correct Answer : C
Answer for Question No. 3
Correct Answer : B
Answer for Question No. 4
Correct Answer : D
Answer for Question No. 5
Correct Answer : A
Answer for Question No. 6
Correct Answer : B
Answer for Question No. 7
24.84 bar
Answer for Question No. 8
272.9 kJ
Answer for Question No. 9
32.7 bar
Answer for Question No. 10
378.35 kJ