Apparatus:
Long hard-glass tube closed at bottom fitted on vertical stand, Engine oil or glycerin, marker, plumb line, meter rule, screw Gauge, digital stop watch, steel balls, strong.
PROCEDURE:
Observe and record the temperature of the Viscosity of a fluid is very much affected by temp set up the tube in vertical position with help of plumb Line and by adjusting the leveling screws. On the glass Tube make a small horizontal line (D) with help of them Marker 5 cm. above the bottom. Make another Horizontal line © exactly 10cm. above the first line similarly, make two more lines (B and A) each at 10 cm Distance above the second mark. In this way. The lower Portion of the tube is divided into three segments each of length 10 cm. Fill the tube with engine oil or glycerin nearly up to the t Take a small steel ball and measure its diameter with Screw gauge. Record this diameter in your table of Observations, also calculate the radius of the steel ball and note it in the table. Hold the stop watch in one hand ready to sat Release the steel ball gently just above the surface of Liquid into the tube with the other hand. The ball Descends into the liquid. Start the stop It crosses mark A. press lap time button when the ball Crosses the mark B and quickly note the tine. Restart The stop watch by pressing the lap time button again. Again press the lap time button and not time when the Ball passes the C and D respectively record these three in your table. These three time should be nearly equal if the Ball is descending in the tube with terminal speed Find terminal speed of the ball by the relation; 
and record it in the table. Also calculate the ratio
and record it in the table.Repeat the above steps 3, 4 and 5 several time with balls of different diameters. Find the mean value of
for all these observations.
From the manual of physical constants and properties. Find the values for density of steel.(Ps) and glycerin (Pg.). Record these values. Use the relation
to determine the value of coefficient of viscosity of the liquid.
Again, at the end of experiment, note the room temperature. Find the mean room temperature.
Observation and calculation:
Result: 
PERCAUTIONS:
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The apparatus must of vertical.
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Time must be noted carefully.
VIVA VOICE
Q.1 Define terminal velocity.
Ans. A constant velocity that is attained by a body which is moving in A fluid.
Q.2 How can the terminal velocity by a body be decreased? Give Example.
Ans. By increasing its effective radius. For example, parachute.
Q3 How is the viscosity of a fluid affected by temperature?
Ans. With increase to temperature, viscosity of liquid decreases but that of gases increases.
Q.4 What is meant by viscosity?
Ans. The resistance between two layers of liquid is called viscosity.
Q.5 What is the unit of viscosity?
Ans. The unit of viscosity in SI unit system is Ngm2
Q.6 What is free fall body?
Ans. A body which falls under the action of gravity (in irregular way)
