CP4 Determine The Viscosity Of A Liquid

Question 1

How?

Answer 1

Fill up a measuring cylinder with washing up liquid to around 200cm mark

Measure the mass of a ball and find its diameter using a micrometre and use this to find its density

Drop the ball and start the stopwatch late so it’s reached terminal velocity
Repeat and make a meantime

Do the same thing for different-sized balls

Question 2

How to reduce uncertainty?

Answer 2

Keep the temperature the same
Use larger distances to reduce human reaction time
use light gates and data loggers
make sure the laminar flow
Make sure eye level with the rubber band when starting time

Question 3

What happens if the diameter of the tube is too small?

Answer 3

The experiment may not be valid as may not be in a laminar flow

Question 4

What may be wrong with using light gates?

Answer 4

They rely on breaking a beam and this may be hard since the liquid is coloured

Question 5

Why would the ball falling near the ends of the cylinder cause it to not be in laminar flow?

Answer 5

The surrounding fluid will accelerate upwards causing no laminar flow.