# ISRO General-Awareness

ISRO Scientist Engineer Sample Paper

Mechanical Engineering

1. Only rocket engines can be propelled to space because
a) They can generate very high thrust
b) They have high propulsion efficiency
C) These engines can work on several fuels
d) They are not air-breathing engines

2. The universal gas constant of a gas is the product of molecular weight of the gas and
a) Gas constant
b) Specific heat at constant pressure
c) Specific heat at constant volume
d) None of the above

3. A spherical shaped vessel of 1.4 m outer diameter is 90 mm thick. Find the rate of heat leakage, if the temperature difference between the inner nd outer surfaces is 220°C. Thermal conductivity of the material of the sphere is 0.083 W/m K.
a) 0.2 kW
b) 0.5 kW
c) 1.088 kW
d) 1.6 kW

4. The temperature distribution at a certain input of time in concrete slab during curing is given by T = 3x2 +3x+16where x is in cm and T is in K. The rate of change of temperature with time is given (a = 0.0003 cm2/sec
a) 0.009 K/sec
b) 0.0048 K/sec
c) -0.0012 K/sec
d) -0.0018 K/sec

5. Chances of occurrence of cavitation are high if the
a) Local pressure becomes very high
b) Local pressure falls below the vapour pressure
c) Thoma cavitation parameter exceeds a certain limit
d) Local temperature becomes low

6. The buoyancy depends on
a) Mass of liquid displaced
b) Viscosity of the liquid
c) Pressure of the liquid
d) Depth of immersion

7. A centrifugal pump with peripheral speed `V' was selected for a total lift of 100 m. Actually pump was to be operated for a total lift of 400 m. The peripheral speed should actually be (other conditions remaining same)
a) 2V
b) 4V
c) 8V
d) 1V

8. A pipeline connecting two reservoirs has its diameter reduced by 20% due to deposition of chemicals. For a given head difference in the reservoirs with unaltered friction factor, this would cause a reduction in discharge of
a) 42.8%
b) 20%
c) 17.8%
d) 10.6%

9. An open rectangular box of base 2m x 2m contains a liquid of specific gravity 0.80 up to a height of 2.5 m. If the box is imparted vertically upward acceleration of 4.9m/s2, what will be the pressure on the base of the tank?
a) 9.81 kPa
b) 19.62 kPa
c) 36.80 kPa
d) 29.40 kPa

10. The value of k for which the lines 2x+ y-1= 0,4x+3y -3 = 0 and 3x + ky - 2 = 0, are concurrent is
a) -2
b) 3
c) 2
d) -3

11. Materials exhibiting time bound behavior are known as
a) Visco elastic
b) Anelastic
c) Isentropic
d) Resilient

12. Shrinkage allowance is made by
a) Adding to external and internal dimensions
b) Subtracting from external and internal dimensions
c) Subtracting from external dimensions and adding to internal dimensions
d) Adding to external dimensions and subtracting from internal dimensions

13. Machinablity depends on
a) Microstructure, physical and mechanical properties and composition of workpiece material
b) Cutting forces
c) Type of chip
d) Tool life

14. Spinning operation is carried out on
a) Hydraulic press
b) Mechanical press
c) Lathe
d) Milling machine

15. Acceptance sampling is widely used in
a) Batch production
b) Job production
c) Mass production
d) All of the above

16. Gratings are used in connection with
a) Flatness measurement
b) Roundness measurement
c) Surface texture measurement
d) Linear displacement measurements

17. Which of the following errors are inevitable in the measuring system and it would be vainflul exercise to avoid them
a) Systematic errors
b) Random errors
c) Calibration errors
d) Environmental errors

18. Maximum shear stress in Mohr's circle is equal to
b) Diameter of circle
c) Center of circle from y-axis
d) Chord of circle

19. If a material expands freely due to heating it will develope
a) Thermal stresses
b) Tensile stress
c) No stress
d) Bending

20. A metal pipe of I m diameter contains a fluid having a pressure of 10 kgf/cm2. If the permissible tensile stress in the metal is 200 kgf/cm2, then the thickness of the metal required for making the pipe would be
a) 5 mm
b) 10 mm
c) 25 mm
d) 20 mm

21. In a single reduction, a large velocity ratio is required. The best transmission is
a) Spur gear drive
b) Helical gear drive
c) Worm gear drive
d) Bevel gear drive

22. If two bodies one light and other heavy have equal kinetic energies, which one has a greater momentum
a) Heavy body
b) Light body
c) Both have equal momentum
d) It depends on the actual velocities

23. If two bodies one light and other heavy have equal kinetic energies, which one has a greater momentum
a) Heavy body
b) Light body
c) Both have equal momentum
d) It depends on the actual velocities

24. Which of the following is not a scalar quantity
a) Time
b) Mass
c) Volume
d) acceleration

25. Which of the following stresses are associated with the tightening of a nut on a stud?
1. Tensile stresses due to stretching of stud.
2. Bending stresses of stud.
3. Transverse shear stresses across threads.
4. Torsional shear stresses in threads due to frictional resistance.
Select the correct answer using the codes given below:
Codes:
a) 1,2 and 3
b) 1,3 and 4
c) 2,3 and 4
d) 1,2 and 4

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