Viscosity Races – investigating the flow of liquids

It is so annoying when get to the end of a ketchup bottle and you have to keep banging to get that last bit out. Why is this? Because ketchup is thick and does not flow as easily as other fluids. We call this resistance to flowing viscosity.

The rate at which different fluids flow can vary considerably.

So how about having races to test them!

 

What you will need:

Stop watch/tape measure

A ramp – we used a table that we took two legs off.

 

Different fluids to test  

We used whole milk, ketchup, chocolate sauce, orange juice and cooking oil

Viscosity races - investigating the flow of fluids, Science Sparks

The different fluids

Deciding what to measure

  • you could decide to time how long it takes for all five fluid to reach the bottom of the table
  • you could decide to measure how far they have travelled after a certain time

How to make the test fair

You need to consider the things that could impact on it not being a fair test – this could include things like

  • ensuring the volume use use is the same for all fluids
  • ensuring that you time the flow for the same distance
  • ensuring that measure after a set time for each.
  • ensuring you repeat the investigation 3 times and take a mean result
  • The gradient of the ramp is the same for each fluid

Method

You can either do one at a time – this is easier for recording time, or tip them all at the same time if you want them to get to the bottom of the table.

Let them flow for the set time you have decided, or time them until they all reach the bottom.

You can record your results in a table.

Viscosity races - investigating the flow of fluids, Science Sparks

Tip and time!

Results 

Viscosity races - investigating the flow of fluids, Science Sparks

Results table 1

Viscosity races - investigating the flow of fluids, Science Sparks

Results table 2

 

We decided to wait until they got to the bottom, but had to stop the experiment as it was clear the ketchup was never going to make it! Next time we will try with measuring the distance travelled!

Have fun

Kerry 

There are 21 comments

  1. dottycookie

    I help to run an after school science club for KS2 children – this looks like a great mixture of messiness and investigation for some of our younger ones. Brilliant! Thank you!

  2. The Buzz on Bees

    […] of liquids: honey and molasses (thick) are notably viscous; water and apple juice (thin) aren’t. Viscosity Races is a great experiment investigating viscosity for ages 5 and up. You’ll need a homemade ramp, an […]

  3. Andrea

    Good day I would like to ask if there is a specific measurements like the measure of height and length of the ramp. btw thank you for the information.

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