PROBLEM: To observe the force of cohesion in water.
MATERIALS: Two glasses of water, tooth pick, tissue paper, paper clip, straight pin.
PROCEDURE AND OBSERVATION:
1. Fill glass with water.
2. Place a paper towel under the glass.
3. Place a one inch square of tissue paper on the surface of the water.
4. Gently place straight pin on the tissue paper, so that the pin will rest on the tissue paper.
5. Now, gently push the edges of the tissue paper under water, with the tooth pick. Try not to touch the pin.
6. Gently continue to push the tissue paper until it sinks.
7. If your pin sinks, be sure to thoroughly dry it, before you try again.
8. Now, repeat the above steps with a paper clip.
9. Now, try to repeat the step 8 floating a paper clip, but this time put a drop of detergent into the glass. What happens?
10. Obtain two pieces of wax paper and place a few drops of clean water on it on one piece. On the other piece of wax paper use the water that had the drop of detergent in it. Compare the shape of the drops on both wax papers.
11. Obtain a capillary tube, and just touch the water that is in the glass. ( a capillary tube is a thin walled and a very small diameter glass tube and is about several inches in length, sometimes used get small quantities of blood from a pin prick). Describe what happens.
QUESTIONS:
1. Define cohesion -
2. Define adhesion -
3. Define capillary action -
4. List five examples of cohesion.
5. List five examples of adhesion.
6. Define force -
7. Give two examples where cohesion can be helpful.
8. Give two examples where adhesion can be helpful.
9. List one Bible reference ( write the entire verse ) where cohesion or adhesion is implied.
10. Where can adhesion be harmful? Explain your answer.
11. Why did the pin and paper clip float?
12. What forces are responsible for keeping the paper clip afloat?
13. Look very carefully at the surface of the water, when the paper clip is floating, describe the surface.
14. What happens when there are drops of clean water on the wax paper? Describe their shape as compare to the drops of detergent water on wax paper.
15. Define meniscus.
16. Why is there a meniscus formed in a graduated cylinder when measuring water?
17. If you ever get a chance, at a dentist's office, or a science lab; carefully observe the mercury shape. Explain why the surface of the mercury is curved downward.
18. Explain what happened in the capillary tube. Explain why it happened.
19. How is it possible for water to travel hundreds of feet up a tree into the leaves, where it is needed.
20. Find out why wicks of lamps and possible candles are made of not cotton, but linen.
See notes for answers.
Side tip!
How to exterminate fleas by drawning! ( Not tested ) Shared by a friend.
Use a large flat dish with water in it, place a drop of detergent in the container. And at night leave a very small night light suspended over the container. The fleas will be drawn to the light source.