ESAS August 15, 2021

Question 1

1. A new engine design incorporates a piston that contains 0.60 kg of steel (specific heat = 470 J/kgK) and 1.20 kg of aluminum (specific heat = 910 J/kgK). How much heat is required to raise the piston from an initial temperature of 20 degree C to its operating temperatures of 160 degree C? *
   192. 36 kJ
   205. 520 kJ
   198. 84 kJ
   185. 78 kJ

Answer 1

192.36 kJ

Question 2

11. A force of 120 N has a rectangular component of 84 N acting along a line making an angle of 20 degrees counterclockwise from the positive x axis. What angle does the 120-N force make with the positive x axis? *
    62. 4 degrees
    65. 6 degrees
    72. 5 degrees
    54. 2 degrees

Answer 2

65.6 degrees

Question 3

12.	A solid circular shaft, running at 300 rpm transmits 2 MW and corresponding maximum shear stress produced is 110 MPa. Calculate the suitable diameter of the shaft. *
		234 mm
		144 mm
		134 mm
		244 mm

Answer 3

144 mm

Question 4

16. Steam enters a turbine stage with an enthalpy of 3628 kJ/kg at 70 m/s and leaves the same stage with an enthalpy of 2846 kJ/kg and a velocity of 124 m/s. Calculate the work done by the steam. *
    988. 7 kJ/kg
    776. 8 kJ/kg
    998. 7 kJ/kg
    766. 8 kJ/kg

Answer 4

776.8 kJ/kg

Question 5

24.	An iceberg having a S.G. = 0.92 floats in salt water having a S.G. = 1.03. If the volume of the ice above the water surface is 1000 cu. m., what is the total volume of the iceberg? *
		8634 cu. m.
		8364 cu. m.
		9364 cu. m.
		9634 cu. m.

Answer 5

9364 cu. m.

Question 6

25.	The work of a polytropic (n = 1.21) compression of air (Cp / Cv = 1.4) in a system with moving boundary from P₁ = 15 psia, V₁ = 1.0 cu. ft. to P₂ = 150 psia, V₂ = 0.15 cu. ft. is *
		1080 ft-lb
		6862 ft-lb
		5150 ft-lb
		2700 ft-lb

Answer 6

5150 ft-lb

Question 7

28.	Neglecting the change of gravity with elevation, estimate the speed of a satellite must have to orbit the earth at an elevation of 100 km. Earth's radius = 6,400 km. *
		6,000
		4,000
		8,000
		10,000

Answer 7

8,000

Question 8

31.	A light beam in air is incident on the surface of a pond, making an angle of 20 degrees with respect to the surface. What is the angle of refraction? *
		20 degrees
		70 degrees
		60 degrees
		45 degrees

Answer 8

45 degrees

Question 9

35. How far is the object from the image formed by a converging lens of focal length 50 cm, if the real image formed is 1.5 times larger than the object? *
    298. 43
    198. 45
    290. 87
    208. 33

Answer 9

208.33

Question 10

46. A body weighs 200 N in air and 125 N when submerged in water. Its specific gravity is nearest *
    2. 31
    2. 49
    2. 54
    2. 67

Answer 10

2.67

Question 11

65.	A student determined to test the law of gravity for himself walks off a skyscraper, stopwatch in hand, and starts his free fall (zero initial velocity). Five seconds later, Superman arrives at the scene and dives off the roof to save the student. What must be the height of the skyscraper so that even Superman can't save him? (Assume that Superman's acceleration is that of any freely falling body). *
		200 ft
		400 ft
		300 ft
		500 ft

Answer 11

400 ft

Question 12

73.	A tank contains 3 cubic feet of 120 psig air at 80°F. How many tires of volume 1.2 ft³ can be inflated to 28 psig at 80°F? *
		3
		4
		5
		8

Answer 12

5

Question 13

93. What is the critical angle between carbon disulfide and air? (The index of refraction for Carbon Disulfide is 1.643) *
    31. 3 deg
    37. 4 deg
    33. 1 deg
    34. 7 deg

Answer 13

37.4 deg

Question 14

98.	A refrigerator gives off 3 J of heat for every joule of mechanical energy input. Its coefficient of performance is *
		1
		4
		3
		2

Answer 14

2