# IB Physics Torricelli's Law

## Recommended Posts

Hi,

I would like to investigate the effect of changing the height on the velocity of the fluid coming out of the cylinder but need help. My school has a spouting cylinder with 4 holes (not enough data?) and I am confused as to how I should find the velocity. My teacher said I should calculate the velocity via projectile motion but wouldn't it be better to find the flow rate per 10 seconds and then from there find the velocity by multiplying the flow rate by the area of a cylinder?

Overall, I am attempting to prove Toricelli's law by showing that the velocity of the fluid coming out at different heights is the same as the velocity when a drop of water is dropped from that certain height?

How can I do this?

I really want to get high marks in this physics IA.

##### Share on other sites

I like the volumetric flow rate method, except you would be dividing by area of the hole (that is, velocity through the hole) which may be subject to large errors because of how small it is.

##### Share on other sites

Hi.

Is there any other way to minimise the large errors or should I have two graphs, (one which contains the errors/and the other that does not), to show the significance of this error?

Also would 5 holes be enough? I plan on making 25 trials for each hole to make it as accurate as possible. Finally, to measure the flow rate, would I measure how much volume is lost in a given amount of time, by using a separate beaker to collect the fluid out (quite difficult as water can spill) or should I measure how much water has been lost through the spouting cylinder? This is the part I am unsure of.

##### Share on other sites

I mean that the error is in the determination of the area of the holes. Say the hole is 10 mm wide but you measured 9 mm, there would be fairly large systematic errors. That's not something having 25 trials would solve. Part of experiment design includes doing only what is necessary. Suppose 25 trials rather than 5 trials only make the confidence interval smaller by 2%, and there is some other source of error that contributes to 10% error, than there is no point doing that many trials. You should weigh all sources of error and eliminate the most important ones before the experiment.

I am not familiar with the exact the equipment you have, and it is really not my responsibility to walk you through the design. Your largest concern was whether there was a way to experimentally determine the velocity, and the answer is yes there is. As for the details of how to minimize spills, it's just a matter of taking precautions and handling the apparatus with care.

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
• Create New...