TODAY’S OUTCOMES:

- Review how siphons work to transport fluids

- Learn how to construct series circuits using different electrical devices

- Define and study electrical current

ELECTRICITY

SUN AND MOON- Observation of the sun & moon; recording of a sun shadow plot

Flow rate at A = Flow rate at B = Flow rate at C = Flow rate at D = Flow rate at E;

All the flow rates in the tube are equal.

> When you did the experiment shown in the diagram, you only measured the flow rate at location E. However, water is also flowing through the tube at locations A-D. If you could measure the flow rate at these locations, how would your measurements compare to that at location E, and how do you know?

Flow rates along the same tube MUST all be equal, or else water would be building up somewhere!

> Filling a backyard swimming pool is a slow business! My neighbor Margie says you should use the hose nozzle, set to make a stinging jet of water, because this will speed the process up. Louise says this is a bad idea, and that it will actually take longer Margie's way; she's better off with a hose without a nozzle. Please discuss Margie's idea, and explain who is right, making some connection to the concepts introduced in today’s activities.

It is not possible for the nozzle to speed up the delivery of the water; only increasing the pressure produced at the water source (spigot) can increase the flow rate. Adding a hose nozzle will only make it more difficult for water to pass through the hose; even though the water speed is faster, the flow rate is actually somewhat slower.

SIPHONS MOVE A FLUID FROM A HIGHER TO LOWER LEVEL

Flow continues until water level between both containers is even.

Water can flow upward through the tube, as long as the water level in the source container is higher than the water destination.

d

A larger distance d generates a higher flow rate.

gravity

pressureGravity drains the end of the siphon, generating pressure inside the tube.

WHY ARE WE STUDYING SIPHONS?In the next few lessons, we will exploit siphons

as a useful analogy to the more abstract concepts underlying electric circuits.

top

bottom

Flow between top and bottom Flow between positive and negative

WHAT YOU ARE EXPECTED TO KNOW:

- How to construct and use a siphon and measure flow rate

- How flow rate is related to water level difference

- Analogies between fluid flow in a siphon system and properties of electricity in a circuit (These will be considered in upcoming activities.)

TODAY’S OUTCOMES:

- Review how siphons work to transport fluids✓

- Learn how to construct series circuits using different electrical devices

- Define and study electrical current

ELECTRICITY

SUN AND MOON- Observation of the sun & moon; recording of a sun shadow plot