For my experiment, I want to investigate the relation between height and velocity using Torricelli's law. I would like to know how I would measure the flow rate from volume in a spouting cylinder.

  • $\begingroup$ A calibrated orifice? $\endgroup$ – user207455 Jun 26 at 18:15
  • $\begingroup$ What is a calibrated orifice? $\endgroup$ – Alireza ghasemi Jun 26 at 18:17
  • $\begingroup$ Also is there any other simpler way of measuring flow rate. Since flow rate is volume per second, is there an instrument where I can measure the volume per 5 second. $\endgroup$ – Alireza ghasemi Jun 26 at 18:18

You can measure the velocity by measuring how far the water jet gets before it strikes the ground.

Flow velocity

Suppose the jet takes a time $t$ to fall the vertical distance $h$ to the ground. This time $t$ will be given by the SUVAT equation:

$$ h = \tfrac{1}{2}gt^2 $$


$$ t = \sqrt{\frac{2h}{g}} $$

Then the horizontal distance travelled is:

$$ s = vt = v\sqrt{\frac{2h}{g}} $$

And we simply rearrange this to get the outflow velocity $v$:

$$ v = s\sqrt{\frac{g}{2h}} $$


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