FM & HM -Assignment.

Colege Time table changed, this time table applicable up to 1st semester.

TH EORY QUESTIONS

1. Define fluid. Explain different types of fluids.

2. State Newton’s law of viscosity and explain its importance in fluid motion. Give examples of its applications. Explain the effect of temperature on viscosity of water and that of air.

3. Define surface tension. Discuss the factors effecting surface tension.

4. Discuss the influence of viscosity, specific gravity and surface tension on fluid motion.

5. What are the absolute and kinematic viscosities? What are their units? Derive expressions for the same. Discuss the factors influencing them.

6. Derive expressions for capillary rise and capillary depression of a liquid.

PROBLEMS

1. If 5.27cm³ of certain oil weighs 4482kg, calculate the specific weight, mass density and specific gravity of the oil.

2. A glass tube 20mm diameter contains a mercury column with water above the mercury. The surface tension of mercury in contact with water is 0.36N/m. Determine the capillary depression of the mercury. Take q=130°.

3. A 15cm diameter vertical cylinder rotates concentrically inside another cylinder of diameter 15.10cm. Both cylinders are 25cm high. The space between the cylinders is filled with a liquid whose viscosity is unknown. If a torque of 12.0Nm is required to rotate the inner cylinder at 100rpm, determine the viscosity of the oil.

4. Abody weighing 45 Kg with flat surface area of 930cm² slides down lubricated inclined plane making a 30° angle with the horizontal. For viscosity of 1Poise and body speed of 3m/s, determine the lubricant film thickness.

5. The velocity distribution over a flat plate is given by u=(y/3)-y² in which 'u' is the velocity in m/s at a distance of 'y' metres above the plate. Determine the stress at y=0 and take µ=0.835N-s/m².

6. If the surface tension at air water interface is 0.073N/m, what is the pressure difference inside and outside of an air bubble of 0.01mm diameter?

7. Glycerin has a density of 1260Kg/m³ and kinematic viscosity of 0.00183m²/sec. what shear stress is required to deform this fluid at a strain rate of 10⁴sec^-1.

8. A thin plate is placed between two flat surfaces ‘h’ cm apart such that the viscosity of liquids on the top and bottom of the plate are µ₁ and µ₂ respectively. Determine the position of the thin plate such that the viscous resistance to uniform motion of the plate is minimum. Assume ‘h’ to be very small.

9. A piston 9.95cm diameter works in a cylinder 10cm diameter, 12cm long. The space between the two is filled with a lubricating oil of viscosity 0.65Poise. Calculate the speed of the piston through the cylinder under the action of the axial force of 5.0N.

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

11. A plate 0.025mm distant from as fixed plate moves at 50cm/s and requires a force of 1.471N/m² to maintain this speed. Determine the fluid viscosity between the plates in Poise.

12. A 25mm wide vertical gap of infinite length contains an oil of viscosity 3.6Pa-s. A metal plate 1.2m length, 1.3m width and 0.018m height weighing 45N is to be lifted through this gap at a constant speed of 0.15m/s. Estimate the force necessary to lift the plate.