Rate of water flow experiment question

[Mike Shandon]

Hi, I am mike from australia, I am new to the forums and am having trouble answering the question below, I have included some information on the experiment as well.

You are given a water bottle with a pin sized hole in the bottom, and a line drawn around the bottle at the level that 50cm3 of water would occupy. You are asked to fill the bottle with 350cm3 of water, and then record the amount of time it takes to reach the 50cm3 marked, essentially you are letting out 300cm3 of water, from this you can go on to calculate the water flow rate.

The question I am having trouble on is:

- Explain why you stop timing when the water level reaches 50cm3?

A possible solution I thought of was, that the water flow rate would decrease, if the bottle was filled to 300cm3 and allowed to reach zero, therefore giving an inaccurate answer.Thank you in advance for any help

 

[mfb]

A possible solution I thought of was, that the water flow rate would decrease, if the bottle was filled to 300cm3 and allowed to reach zero, therefore giving an inaccurate answer.

I agree. The water flow rate approaches zero, so it is hard to tell when the bottle is "exactly empty".

 

[drvrm]

Explain why you stop timing when the water level reaches 50cm3?

A possible solution I thought of was, that the water flow rate would decrease, if the bottle was filled to 300cm3 and allowed to reach zero, therefore giving an inaccurate answer.Thank you in advance for any help

we do such experiments with certain conditions like flow should be streamlined and not turbulent-
other dissipative forces like adhesion of the liquid to the walls may be neglected and no vortices formed- well i do not have any idea about the diameter of the jar/bottle
- may be the last 50cc of liguid may not be a streamlined flow-so that precaution is wise enough.

 

[Mike Shandon]

Thank you for the replies, they were very helpful