Viscosity - Comparing the viscosities of different liquids.

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Blerim Shahaj        -  -        Physics Course Work


Comparing the viscosities of different liquids.

Introduction and Hypotheses

If we move through a pool of water we experience a resistance to our motion. This shows that there is a frictional force in liquids. We say this is due to the viscosity of the liquid. The viscosity of a liquid is a measure of its resistance to flow and is caused by the internal friction of the liquid. If the frictional force is comparatively low as in water the viscosity of the liquid is low. If the frictional force is large, as in glue or glycerine, the viscosity of the liquid is high.  We can compare roughly the viscosity of two liquids by filling two measured cylinders with each of them, and allowing identical small steel ball bearings to fall through each liquid. The ball bearing falls slower through the liquid with higher viscosity.

I am going to investigate three different liquids and compare their viscosities. The liquids I am going to investigate are: oil, washing liquid and honey.

I predict that the viscosity of the honey will be the highest due to the fact that honey flows much slower than oil or washing liquid.

I predict that the upthrust force will be much bigger in honey due to higher density in honey. The upthrust force will be the lowest in oil since this has the lowest density of the three liquids under consideration.

Due to high value of upthrust force the value of terminal speed in honey will be lower than in the other two liquids.

I predict that the viscosity does not necessarily depend on density. For example I think that viscosity in oil would be higher than viscosity of water although the density of oil is lower than density of water.


Before I start my main experiment I have chosen to do a risk assessment, which is shown below.

Risk Assessment:

  • I will handle all the liquid cylinders carefully
  • I am going to take extra care when filling the cylinders with liquid
  • I will carefully take out the ball bearing once inside the cylinder with liquid with a magnet.
  • I will use safety glasses in case the cylinders break out

Apparatus required to carry out the experiment:

  1. Ruler
  2. Clamp
  3. Clamp stand
  4. Safety glasses
  5. G Clamp
  6. 3 Cylinders
  7. Magnet
  8. Ball bearings
  9. Honey
  10. Washing liquid
  11. Oil
  12. Flat pieces of wood
  13. Container
  14. Table
  15. Tape
  16. 3 Timers (Stop Watch)
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Below is a diagram of the experiment I am going to carry out.

  1. I will set up the apparatus as shown in the diagram above. Using the G clamp I will attach the clamp stand to the table and make sure that it is in level and stable. Then I will clamp the cylinder on the clamp stand and ensure that it doesn’t slip out.


  1. I will carefully fill the cylinder with liquid so that its not poured out on the floor or on me. The cylinder can be emptied by ...

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