# Homework Help: Problem help again

1. Feb 1, 2004

### mindhater

The drinking fountain outside your class shoots water 15 cm straight up in the air from a nozzle diameter of .58 cm. The pump at the base of the unit (90 m below the nozzle) pushes water into a 2.2 cm diameter supply pipe that goes up the nozzle. What is the absolute pressure provided by the pump?

i assume, it's calculate the pressure using (g)(h)(density) + atm pressure = absolute pressure

but i'm not sure...so if there's ne advice or something i'm missing...thx

2. Feb 2, 2004

### sickboy

This one can be solved using Bernoulli's equation. There might be easier wayto do it, but this how I'd break it down (I suppose you are familiar the equation).

On the left side, there are pressure (supplied by the pump), velocity ( you can calculate by recognizing that $A_1*v_1=A_2*v_2$) and potential energy ( it makes sense to use this point as zero point for pot.energy). On the right side you have pressure again, velocity and potential energy.

There shouldn't be any unknowns remaining...

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