Physics Answers

3. A working substance undergoes a reversible non flow process during which P

= (-3V + 100) psia, where V changes from 10 ft3/min to 30 ft3/min. The change

of internal energy for the process is – 100 BTU/min. For a non-flow process,

determine a) work (BTU/min) b) heat transferred (BTU/min).

1. A water pump operating under steady flow conditions delivers 33 kgm/s of

water from initial pressure of 82 kPaa to a final pressure of 275 kPaa. The

diameter of the inlet pipe is 15 cm and the diameter of the discharge pipe is

10 cm. What is the steady flow work if Q=0 and density of water is 1000

kgm/m3?

The pressure in the pressurized water tank is measured by a multi-fluid manometer

with one end open to the atmosphere. Determine the absolute pressure of air in the

tank (pressure at point 1) assuming that the air pressure is uniform. The densities of

mercury, water and oil are 13,600 kgm/m3, 1000 kgm/m3, 850 kgm/m3, respectively. h1

= 20 cm, h2 = 30 cm and h3 = 46 cm

Barometric Pressure is 29.89 in Hg. Convert the following

a. 68 psig to mm Hg absolute

b. 100 kPag to psia

c. 1000 mm Hg absolute to kPag

d. 5 psia to in Hg vacuum

A 700 lbm rocket is accelerated at a rate of 20 ft/s2. What total force is required in lbf

if: a) the rocket is moving horizontally and without friction, b) the rocket is moving

vertically upward in a location where g = 31 ft/s2.

Four bodies are located in a region where g = 9.67 m/s2

.Body1 = 750 gm; Body2 = 4 poundals; body3 = 4.5 N and body4 = 32.2 lbf.

a) What is the total mass expressed in lbm?

b) What will be the total weight (lbf) if the bodies are located 15,000 ft above

the earth’s surface? (gravitational acceleration decreases by 0.003 ft/s2

for every 1000 ft ascent above sea level)

c) At what distance (miles) from the earth’s surface will these objects weigh

zero.

Spheres A and B have the same initial positive charge qO.The magnitude of the repulsive electric force between the two spheres is 14.4 N when separated by a distance of 0.03 m.

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a) Find the initial q0

b)The spheres are then allowed to touch each other and then separated.Find the electric force between them if the radius of sphere A is three times that of sphere B.

Two resistances of 10 and 15 ohms each respectively are connected in parallel. The two are then connected in series with a 5-ohm resistance. What is the equivalent resistance?

The block in figure reaches a velocity of 12m/s in 30m, starting from rest

Compute the coefficient kinetic friction between the block and the ground.

• 718 N
• P = 268 N

a styrofoam cylinder, filled with water, sits on a table. you then poke a small hole through the side of the cylinder, 20 cm below the top of the water surface. what is the speed of the fluid emerging from the hole?