The Siphon

The siphon ~30 Minutes

Description: An investigation of the siphon.

Objective: To understand how a siphon works.

Outcomes:
-demonstrate how force can be applied to move an object (grade 1)
-identify the properties of solids, liquids, and gases (grade 2)
-demonstrate how various forces canaffect the movement of objects (grade 5)

Materials: about 30 paper clips in a chain, pop bottle, 2 buckets or large containers, one length of tubing (about 2 feet)

Doing it:
A1. Take the string of paper clips and loop them over the pop bottle. Have someone hold two hands just underneath the bottle and pile and equal number of paperclips in each.
A2. Slowly lower one hand until the paper clips move. What is the difference in height?

Fig 1.1 - While lowering the left hand, the clips started to move from right to left.
Fig 1.2 - Filling the tube with water.

B3. Put your finger over the ends of the tube to plug them and quickly put one end out in each bucket.
B4. Take your finger off the ends of the tube and watch the flow of water. C1. If one person is holding each container, what happens if you move them up and down relative to each other? How much further down does a container have to be before there is a flow of water?

C1. If one person is holding each container, what happens if you move them up and down relative to each other? How much further down does a container have to be before there is a flow of water?

Fig 1.3 - The containers next to each other.
Fig 1.4 - One container raised, the siphon will flow from one to the other until the levels are even.

Notes:

Explanation: The liquid inside the siphon is composed of atoms which are attracted to each other (that is what makes them different from a gas , where the atoms bounce around and don’t see each other much). As long as the outlet of the tubing is lower than the level of the water in the upper bucket, the weight of the water pulls the rest of the column of water with it just like the chain of paperclips, with each clip being a molecule and the chain representing the intermolecular forces. Note that the water(and paperclips) are pulled uphill for part of its trip.

Created by Brock Watson July 2007