PVPIT SE [Mech] Question Bank for Mid Term Test Aug 09

UNIT NO. 1
1. Justify following statements:-
1. In soldering process, metal flows through a narrow gap.
2. Mercury spilled on floor cannot be collected by hand.
3. Lubricating oil film prevents internal leakage in hydraulic
cylinders.
4. Water can be boiled at room temperature.
5. Small insects can walk on water.
6. Edible oil floats on water.
7. Mercury is preferred as manometric fluid.
8. Change in temperature causes change in viscosity of fluid.

2. An oil of viscosity 5 poise is used for lubrication between a shaft and sleeve. The diameter of shaft is 0.5 m and is rotating at 200 rpm. Calculate the power lost in oil for a sleeve length of 100 mm. The thickness oil film is 1.0 mm

3. A solid cylinder 90 mm dia. rotates inside a fixed cylindrical tube of 95 mm internal dia. and 500 mm length. A narrow gap between the two is filled with oil of viscosity 2 kg/ms .Calculate the power required to rotate the solid cylinder at 240 rpm.

4. A uniform film of oil 0.13mm thick separates two discs, each of 200 mm diameter , mounted co-axially. Ignoring the edge effects, calculate the torque necessary to rotate one disc relative to other at a speed of 7 rev/s, if the oil has a viscosity of 0.14 Pas.

5. Explain the concept of following giving suitable example/application.
1. Surface tension
2. Vapour pressure
3. Capillarity
4. Viscosity

Derive continuity equation in Cartesian co-ordinates.

UNIT NO. 2

Derive an expression for total pressure and centre of pressure for a vertical plane surface immersed in a static mass of liquid.

2. A circular opening, 3m diameter, in a vertical side of a tank is closed by a disc of 3m diameter which can rotate about a horizontal diameter . Calculate
a) Force on the disc
b) The torque required to maintain the disc in equilibrium in the vertical position when the head of water above the horizontal diameter is 6m.

3. A vertical sluice gate is used to cover an opening in a dam. The opening is 2 m wide and 1.2 m high. On the upstream of the gate, the liquid of sp. gr. 1.45, lies up to a height of 1.5 m above the top of the gate, where as on the downstream side, the water is available up to a height touching the top of the gate. Find the resultant force acting on the gate and position of center of pressure. Find also the force acting horizontally at the top of the gate which is capable of opening it. Assume that the gate is hinged at the bottom.

4. A solid cylinder of 200 mm diameter and 800 mm length has its base 20 mm thick and of specific gravity 6. The remaining part of the cylinder is of specific gravity 0.6. State, if it can float vertically in water.

5. What is Pascal’s Paradox?

6. State and prove Pascal’s Law.
7. Show that pressure does not vary in X and Y direction when fluid is stationary and hence derive an expression for pressure at any point in static mass of fluid.

Unit No. 3

1. Derive Euler’s equation of motion and hence Bernoulli’s equation. State the
assumptions made.
2. Gasoline (sp.gr. 0.8) is flowing upwards through a vertical pipeline which tapers from 300 mm to 150 mm diameter. A gasoline mercury differential manometer is connected between 300 mm and 150 mm pipe section to measure the rate of flow. The distance between the manometer tappings is 1 m and gauge reading is 500 mm of mercury. Find 1.Differential gauge reading in terms of gasoline head 2.Rate of flow

3. A pipeline carrying oil (sp.gr. 0.8) changes in diameter from 300 mm at position 1 to 600 mm diameter at position 2 which is 5 m at a higher level. If the pressures at positions 1 and 2 are 100 kN/m2 and 60 kN/m2 respectively and the discharge is 300 lps, determine
1. Loss of head
2. Direction of flow
4. A horizontal venturimeter with inlet and throat diameters 300 mm and 100 mm respectively is used to measure the flow of water. The pressure intensity at the inlet is 130 kN/m2 while the vacuum pressure head at the throat is 350 mm of mercury. Assuming that 3 percent of head is lost in between the inlet and throat, Find :
1. Co-efficient of discharge
2. Rate of flow.
5. A venturimeter has its axis vertical, the inlet and throat diameters being 150 mm and 75 mm respectively. The throat is 225 mm above inlet and venturimeter constant = 0.96. Petrol of sp.gr. 0.78 flows up through the meter at a rate of 0.029 m3/s. Find the pressure difference between inlet and throat.