TEACHERS HANDS-ON
EXPERIMENT
This experiment
has been
designed to
study viscosity
of liquids
Introduction
Viscosity is a measure of a fluid's resistance to flow.
In
other word viscosity of a fluid is basically a measure of how sticky it
is.
Fluids resist the relative motion of immersed objects through them as
well as to the motion of layers with differing velocities (rate of travel)
within them.
It describes the internal friction of a moving fluid. A fluid with high
viscosity resists motion because its molecular makeup gives it a lot of
internal friction.
A fluid with low viscosity flows easily because its molecular makeup
results in very little friction when it is in motion.
Diagram
5cm
A
A
10cm
WOODEN
BLOCK
B
30°
TILE
TILE
Procedure
•
•
•
•
•
•
•
Clean the tile given with a cloth. Draw a straight line about 5 cm
from one edge of tile and label the line as A.
Draw a second line about 10 cm from the first line and label the
line as B.
Place the tile on top of a wooden block so that the tile is placed
at the angle of 30°.
Use a dropper to drop 2 drops of liquid X on the tile above line
A.
Start the stopwatch when liquid X crosses line A and stop the
stopwatch when the liquid reaches line B.
Record the time taken for the liquid X reach line B.
Clean the tile again and repeat steps 3 - 6 with the other liquids
Y and Z.
Procedure
•
Calculate the average travel time from A to B for each liquid.
•
The rate of travel for each liquid tested can be calculated by
using the formula below:
Rate of travel =
Distance traveled (cm)
Travel time (seconds)
Scientific Method
oAim of experiment (2 marks)
oApparatus and Materials (3 marks)
oHypothesis (2 marks)
oVariables (3 marks)
oResults (5 marks)
o Record the rate of travel by the liquids on the tiles in the
table below (4 marks)
o Draw a chart to show the difference between rate of travel
and liquids tested (4 marks)
o Conclusion (3 marks)
o Experimental and safety precautions (2 marks)
o Suggest matter of to improvise the experiment to get an
accurate result (2 marks)
Questions

Suggest how to ensure that the results are reliable and accurate.
(2 marks)

What will happen to the rate of travel if salt is added to liquid X?
Explain. (2 marks)

Predict the rate of travel for liquid Y if the angle of the tile
increased to 60°. Why?(2 marks)

If the tile is replaced with a rough surface, what will happen to the
rate of travel for liquid Z? Explain. (2 marks)

How can you decrease the viscosity of liquids? Explain. (2 marks)
Discussion Session …
Scientific Method Sample Answer
Aim of experiment
To examine the relationship between
viscosity of the various Liquids and its flow
of the liquids

Hypothesis
The more the liquids viscos the slower the
liquids flow

Apparatus and Materials
Liquids X,Y & Z tile, ruler, pencil, stopwatch,
protector

Variables
What to keep the same/Control Variable- Tiles,
Stopwatch, angle
What to change/Manipulated Variable- Liquids
X,Y & Z
What to observe/Responding Variable- Time
Taken for the liquids flow

Results
Liquid
Tested
Travel Time
Trial 1
(s)
Travel Time
Trial 2
(s)
7
4
5
7
Y
14
15
15
15.5
Z
33
31
34
32
X
Travel Time Average
Trial 3
(s)
(s)
 Record
the rate of travel by the liquids on the tiles in
the table below
Liquid Tested
X
Y
Z
Rate of travel
(cm/s)
10/7 = 0.8
10/15.5= 0.5
10/ 33 = 0.33
cm/s
 Conclusion
There more the liquids viscos the slower the
liquids flow. The hypothesis is accepted.
 Experimental
and safety precautions
Handle the tiles with care because it is fragile
 Suggest
matter of to improvise the
experiment to get an accurate result
Design a tools to drop the various liquids in
simultaneously.
Questions Sample Answer
 Suggest
how to ensure that the results are
reliable and accurate.
Do repetition and take the average value
 What
will happen to the rate of travel if
salt is added to liquid X? Explain.
Rate of travel of the liquids X reduced
compare to previous value when without
salt.
Predict the rate of travel for liquid Y if the angle of the
tile increased to 60°. Why?
The rate of travel for liquids y increase because the
potential energy of the liquids y increase.

If the tile is replaced with a rough surface, what will
happen to the rate of travel for liquid Z? Explain .
The rate of travel of liquids z reduced because more
friction happen between the surface and the liquid.

How can you decrease the viscosity of liquids? Explain.
Can mix the liquids with water to dilute the liquids or
increase the temperature of the liquids.
