Extra Credit 1

Pressure and flow

In this virtual laboratory you will investigate properties of fluid pressure and flow.
Link to the simulation:
http://phet.colorado.edu/en/simulation/fluid-pressure-and-flow

The interface

Pressure tab

Flow tab

Water Tower tab

Explorations:

To convince me that you did explore the simulation, submit your answers to Question 1 - 5 on Canvas.

Click the Pressure tab.  Notice what happens under the following conditions.

Question 1:

Reset all.  Make sure there is atmosphere above the basin.  The atmosphere is also a fluid, and its density is roughly constant within a few meters of the ground.  Use the ruler and two pressure sensors to measure the change in pressure (in Pa) over a vertical distance of 2 m.  Then use Pbottom - Ptop = ρhg to find the density of the atmosphere in kg/m3.  What is the density ρ of this atmosphere?

Question 2:

Reset all.  Make sure there is atmosphere above the basin.  Change the fluid density by sliding the density slider all the way to the right to honey.  Fill the basin with honey until the pressure at the bottom is 130 kPa.  What is the height h of the honey in the basin in m?


Click the Flow tab.  Notice what happens under the following conditions.

Reset all.  Choose no friction:

Question 3:

image

Reset all.  Move the yellow handles in the middle of the pipe to their extreme up and down positions, while leaving everything else untouched.  Measure the pressure as close to the lower wall as possible at two different locations in the pipe near the handles pointed to by arrows in the figure above.  What is the pressure difference in kPa?

Reset all.  Turn on friction:

Question 4:

Reset all.  Turn on friction.  Adjust the flow rate so that the speed as close to the wall of the straight pipe as you can measure is 0.6 m/s.  What is the speed of the liquid in the middle of the pipe in m/s?


Click the Water Tower tab.  Notice what happens under the following conditions.

Open the hole in the bottom of the tank.  Match the leakage to keep water level in the tank constant.  Measure the speed of the fluid just as its exits the tank.

Question 5:

Reset all.  How far (horizontally) will a stream of water travel if it exits the water tower at 14 m/s 10 m above the ground?
(Click "Match Release", open the hole in the bottom of the tank, and then click "Fill".  Use the yellow handle to move the tank vertically.)


Now go to Canvas, Assignments, Extra Credit 1.  Use the simulation to help you answer questions 1 - 5.  You can submit twice and the highest score counts.