2016-17 M.E.D., Z.H.C.E.T, A.M.U.

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ME 101/EME101 (Thermal Sciences)

Tutorial (Unit – 1)

Q.1. Two chambers with the same fluid at their base are separated by a piston whose

weight is 25 N, as shown in Fig. 1. Calculate the gage pressures in chambers A and B.

Fig. 1.

Q.2. Two water tanks are connected to each other through a mercury manometer

with inclined tubes, as shown in Fig. 2. If the pressure difference between the two tanks

is 20 kPa, calculate a and ϴ.

Fig. 2.

Q.3. Calculate the pressure generated by an ordinary shoe heel (person of mass 40 kg,

heel 5 cm ˣ 5 cm), an elephant (of mass 500 kg, foot of 20 cm diameter) and a high-

heeled shoe (person of mass 40 kg, heel of area 0.5 cm2). Which one will damage a

wooden floor that starts to yield at a pressure of 4000 kPa?

Q.4. The basic elements of a hydraulic press are shown in Figure 4. The plunger has

an area of 3-cm2, and a force, F1, can be applied to the plunger through a lever

mechanism having a mechanical advantage of 8 to 1. If the large piston has an area of

150 cm2, what load, F2, can be raised by a force of 30 N applied to the lever?

ANS: 12 kN

Fig 4.

2016-17 M.E.D., Z.H.C.E.T, A.M.U.

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Q.5. A U-tube manometer is connected to a closed tank containing air and water as

shown in Figure 5. At the closed end of the manometer the absolute air pressure is

140kPa. Determine the reading on the pressure gage for a differential reading of 1.5-m

on the manometer. Express your answer in gage pressure value. Assume standard

atmospheric pressure and neglect the weight of the air columns in the manometer.

ANS: 66.8 kPa

Fig. 5. Fig 6.

Q.6. A mercury manometer is used to measure the pressure difference in the two

pipelines as shown in Figure 6. Fuel (f = 850 kg/m3) is flowing in A and oil (o = 915

kg/m3) is flowing in B. An air pocket has become entrapped in the oil as indicated.

Determine the pressure in pipe B if the pressure in A is 105.5 kPa.

ANS. pB = 124:9 kPa

Q.7. For the inclined-tube manometer of Figure 7, the pressure in pipe A is 8 kPa. The

fluid in both pipes A and B is water, and the gage fluid in the manometer has a specific

gravity of 2.6. What is the pressure in pipe B corresponding to the differential reading

shown?

ANS: 5508.3 Pa

Fig 7.

2016-17 M.E.D., Z.H.C.E.T, A.M.U.

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Q.8. A weight lies on a piston with a radius r2 = 1.0 m. Determine the force F1 applied

to the piston with radius r1 = 20 cm if the hydraulic jack is in balance. The jack is filled

by an oil with o = 850 kg/m3. Mass of weight is mw = 1000 kg. Neglect the mass of the

pistons. ANS: F1 = 392.4 N

Fig.8.

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Q.13.

Q.14. Compartments A and B of the tank shown in the figure below are closed and

filled with air and a liquid with a specific gravity equal to 0.6 respectively. If

atmospheric pressure is 101 kPa and the press1ure gage reads 3.5 kPa (gage),

determine the manometer reading, h.

[8]

Fig.14.

Q.15. When the reference junction of a thermocouple is kept at the ice point and the

test junction is at the Celscius temperature T, and e.m.f. E of the thermocouple is given

by the equation: E = aT + bT2 ; where a = 0.20 mV/oC and b = -5.0 10-4 mV/oC2

(a) Compute the e.m.f. when T = -100oC, 200oC, 400oC and 500oC, and plot the

graph of E against T in this range.

(b) Suppose the e.m.f. E is taken as a thermometric property and that a temperature

scale T* is defined by the linear relation T* = a’E + b’; and that T* = 0 at the ice

point and T* = 100 at the steam point. Find the numerical values of a’ and b’ and

draw a graph of E against T*.

(c) Find the values of T*, when T = -100oC, 200oC, 400oC and 500oC, and plot the

graph of T* against T.

(d) Compare the Celsius scale with the T* scale.

Q.16. A platinum wire is used as resistance thermometer. The wire resistance was

found to be 10 ohm and 16 ohm at ice point and steam point respectively, and 30 ohm at

sulphur boiling point of 444.6 oC. Find the resistance of the wire at 500 oC, if the

resistance varies with temperature by the relation:

R = Ro (1+αT+βT2)