Study Set Content:
283. A centrifugal pump (efficiency 88%) lifts water through a total height of 40 m from a
reservoir to discharge. Pumping is through 300 m of 75 mm diameter pipe at the rate of 20
liter/s. If pipe friction, f = 0.025, what horsepower is required?
A. 28.4 kW B. 32.2 kW C. 25kW D. 9kW
. 32.2 kW
284. In order to predict the behaviour of a small oil pump, tests are to be made on a model
using air. The pump is to be driven by a 1/20-hp motor at 1800 rpm and a ¼-hp motor is
available to drive the air at 600 rpm. Using specific gravity of oil at 0.912 and density of air
constant at 0.076 lb/ ft3
, what size model should be built?
A. The model should be 2 times as large as the oil pump.
B. The model should be 5 times as large as the oil pump.
C. The model should be 8 times as large as the oil pump.
D. The model should be 10 times as large as the oil pump.
. The model should be 10 times as large as the oil pump.
285. A double-overhung impulse turbine installation is to develop 20,000 hp at 275 rpm under a
net head of 1100 ft. Determine the specific speed.
A. 4.34 B. 6.14 C. 203.61 D. 144
A. 4.34
286. An impulse wheel at best produces 125 hp under a head of 210 ft. By what percent should
the speed be increased for a 290-ft head?
A. 82.25% B. 17.5% C. 72.41% D. 27.59%
B. 17.5%
287. What is the power ratio of a pump and its 1/5 scale model if the ratio of heads is 4 to 1?
A. 20 B. 200 C. 12.5 D. 125
B. 200
288. The speed of a centrifugal pump is doubled. By what factor does the pump head change?
A. 0.125 B. 0.25 C. 4 D. 8
C. 4
289. Compute the specific volume of an air-vapor mixture in cubic meter per kg of dry air when
the following conditions prevail: t = 40°C, w = 0.015 kg/kg, and Pt = 90 kPa.
A. 0.99 m3
/kg B. 0.89 m3
/kg C. 0.79 m
3
/kg D. 0.69 m3
/kg
A. 0.99 m³/kg
290. A coil has an inlet temperature of 70°F and outlet of 80°F. If the mean temperature of the
coil is 130°F, find the bypass factor of the coil.
A. 0.28 B. 1.2 C. 0.82 D. 0.83
D. 0.83
291. Compute the pressure drop of 35°C air flowing with a mean velocity of 5m/s in a circular
sheet-metal duct 400mm in diameter and 25 m long. Use friction factor, f = 0.04, and ρair =
1.3799 kg/m3
.
A. 431.22 Pa B. 221.34 Pa
C 312.24 Pa D. 422.31 Pa
A. 431.22 Pa
292. Pressure difference of 400 Pa is available to force 20°C air through a circular sheet-metal
duct 450 mm in diameter and 25 m long. At 20°C, ρ = 1.204 kg/m3
and take friction factor, f =
0.016. Determine the velocity.
A. 27.34 ft/s B. 43.72ft/s
C. 89.68 ft/s D. 86.98 ft/s
A. 27.34 ft/s
293. A rectangular duct has a dimension of 0.25 m by 2 m. Determine the equivalent diameter
of the duct.
A. 0.50 m B. 0.60 m C. 0.70 m D. 0.40 m
. 0.40 m
294. To what height will a barometer column rise if the atmospheric conditions are 13.9 psia
and 68°F and barometer fluid is mercury?
A. 3.56 ft B. 5.36 ft C. 2.36 ft D. 3.26 ft
C. 2.36 ft
295. To what height will a barometer column rise if the atmospheric conditions are 13.9 psia
and 68°F and barometer fluid is ethyl alcohol? Note: @ 68°F; Pv =138.5 lbf/ft3
and specific
gravity of 0.79 for ethyl alcohol:
A. 79.37 in B. 37.79 in
C. 353.54 in D. 453.53 in
D. 453.53 in
296. What is the pressure 7000 ft below the water surface of the ocean? Neglect
compressibility.
A. 512,000 psf B. 324,500 psf
C. 447,000 psf D. 213,000 psf
C. 447,000 psf
297. If atmospheric air 14.7 psia and 60°F at sea level, what is the pressure at 14212 ft altitude
if air is incompressible? Note: @ 60°F, the density of air is 0.0763 lbm/ft3
; P1 = 14.7 psia.
A. 5.4674 psia B. 7.5304 psia
C. 7.1696 psia D. 7.1966 psia
. 7.1696 psia
298. Water (ρ = 62.4 lbm/ft3
) is flowing through a pipe. A pitot-static gage registers 3.0 inches of
mercury. What is the velocity of the water in the pipe? Note: ρHg = 848.6 lbm/ft3
.
A. 14.7 ft/s B. 41.7 ft/s
C. 71.4 ft/s D. 74.1 ft/s
A. 14.7 ft/s
299. The mass of an outside air at 50°C in an air conditioning unit is 60 kg. Find the temperature
after mixing if the outside air mixed with 40 kg with recirculated air at 35°C.
A. 44°C B. 39°C C. 52°C D. 47°C
A. 44°C
300. A creamery must cool 20,000 liters of milk received each day from an initial temperature
of 29°C to a final temperature of 2°C in 5 hours. If refrigeration losses amount to 10 percent of
the cooling load, what must be the capacity of their refrigerating machine? Note: specific heat
of milk is 3.9 kJ/kg-K and SG = 1.05.
A. 38.5 TOR B. 36.5 TOR
C. 37.5 TOR D. 39.5 TOR
A. 38.5 TOR
262. Air enters a nozzle steadily at 2.21 kg/m3
and 30 m/s. What is the mass flow rate through
the nozzle if the inlet area of the nozzle is 80 cm2
?
A. 0.35 kg/s B. 3.5 kg/s
C. 5.3 kg/s D. 0.53 kg/s
D. 0.53 kg/s
