Question

Help with coming up with ideas for physics final?

Answer 1

We are approaching finals and one of my finals is coming up with scientific questions and a testable hypothesis on a dripping faucet.. That may sound a little confusing, here's the prompt in an image: http://i.imgur.com/pB4eZaJ.png

I'm not asking to do the whole lab for me, I'm simply asking for ideas and variables to test and possibly a hypothesis to formulate out of it. Which observations could I test? What are some scientific questions I could formulate out of it? Any ideas would be very much appreciated. Thanks in advanced.

Answer 2

Things you can measure are:

frequency of drops (or time period between drops)
flow rate (see how much water collects in a fixed time)
temperature of the water (difficult, as it will cool down when flowing out)

How does frequency of drops depend on flow rate?
What is the critical flow rate that you get a continuous stream?

if you have a decent camera, you could try to measure the size of the drops (does it depend on flow rate?)

you can definitely observe their shape by eye (they'll be spherical due to surface tension, rather than the typical cartoony pear shape)

I can't think of much else off the top of my head

Answer 3

Oh, from frequency and flow rate you can calculate average volume of the drops

Answer 4

@broken_symmetry - Thanks so much! That really helps! If you don't mind me asking, which formula/equation would you use to calculate the average volume? Also, what would be the difference between the frequency and flow rate? Would the frequency be how many times they fall per second / minute, and would flow rate be how fast?

Thanks for your help!

Answer 5

What I mean by frequency is how many drops fall in a fixed time period. If you count how many fall in 1 minute and divide that number by 60, you get a frequency in Hertz.

What I mean by flow rate is the volume of water that comes out of the tap in a fixed time. You could put a volumetric beaker under the tap for an hour and work out how many litres flowed per minute or per second or whatever units you want to use.

If you know how many drops fall in a fixed time and if you know what volume of water fell in the same amount of time, you can work out how much water is in each drop.

It's simply flow rate divided by frequency.

Answer 6

@broken_symmetry - Thanks a lot. I am going to put a beaker under a dripping faucet and see how much is gathered in a minute.. Do you think that would work? I will also count how many drops fall.

So let's just say I do this and I get hmm.. 0.5ml of water (random number) and 48 drops..
I would firstly divide 48/60 sec and that would be 0.8 drops per sec? or would it be a drop every 0.8 seconds? Then after that, to figure out the amount of water in each drop, I would divide 48/0.5 ? Except that comes out to 26 and I don't think it's right..

Answer 7

48 drops / 60 seconds = 0.8 drops / second
60 seconds / 48 drops = 1.25 seconds / drop

If you keep track of the units, you won't have any problems.

The rate of flow of water would be 0.5 ml / 60 seconds = 0.0083333 ml / second

Divide flow rate by drop rate you get (0.0083333... ml / second) / (0.8 drops / second) = 0.01 ml / drop

Alternatively if you just use the measurements from the full minute you can do

0.5 ml / 48 drops = 0.01 ml / drop

Answer 8

Thanks so much @broken_symmetry. That really helped.