# I Bernoulli eq

1. Nov 26, 2016

### bluejay27

Why is there less pressure if the velocity of the fluid is increased?

2. Nov 26, 2016

### bluejay27

I obtained the answer! It deals with the continuity equation, where the mass of a moving fluid does not change as it flows. Thus, the volume flow rate has to be equal at all times.

3. Nov 26, 2016

### bluejay27

Nevermind that still does not answer my question. Why is there less pressure when the velocity of fluid is increased?

4. Nov 26, 2016

### bluejay27

You can look at the Bernoulli equation! Since, the left side of its equation is constant, the right side must equal to each other. If there is a smaller cross-section, there will be a higher speed and in order to make the equation equivalent to the left side of the equation, the P at the right side of the equation must decrease.

5. Nov 26, 2016

### Staff: Mentor

That's one of two parts: that's conservation of mass (flow). The other is conservation of energy.

6. Dec 7, 2016

### zanick

ive often wondered what causes the molecules to accelerate. some say that the neck down is a kind of "velocity filter" and allows the high speed vibrations of the molecules to prioritize the ones pointed in the right direction, through.

7. Dec 7, 2016

### Austin Z W

Been a while since I took physics, but I believe that because the left side of the Bernoulli equation stays constant the pressure must vary proportionally with the velocity. So as the water speeds up, it must exert a lower pressure on its surroundings.