Bernoulli's principle with a Garden Hose

Learn Bernoulli's Principle while watering the backyard.   


Appropriate Age Level
7+ 

Materials Needed
Garden Hose
Water Pressure
Something to Spray with Water, preferably plants, not your mom or dad. 

Science Learned
Density - mass per unit volume or the measure of how tightly passed stuff, aka mass, is. (1)

Bernoulli's Principle- states that increase in the speed of moving air or a flowing fluid is accompanied by a decrease in the air or fluid's pressure. (2)

Pressure- the measure of force applied over a unit area.(3)

Activity/Experiment 

1. Gather a garden hose, and hook it up to a spout.

2. Turn on the hose. Note the speed at which the water is exiting the end of the hose.

3. Now put your thumb on the end of the hose, to create only a small slit for the water to exit. The water should now exit the hose at a faster speed.  This is demonstrating Bernoulli's Principle. (4)

4. While watering plants, explain: You have to press your thumb hard against the end of the hose because the water in the hose is under greater pressure in the hose than outside of it.  The pressure in the hose is definitely greater than that of the atmosphere outside the hose.

5. You can make the hole on the end of the hose increase or decrease in size and as the hole decreases in size the speed of the water will increase because there is a larger pressure differentiation and the water wants to get to the lower pressure state as quickly as it can.

6. Enjoy your nicely watered garden all thanks to Bernoulli's Principle!



Time Allotted

5-10 minutes

References 
1. http://www.windows2universe.org/glossary/density_defn.html
2. http://www.ehow.com/how_2247750_explain-bernoullis-theorem-experiment-kids.html
3.http://chemistry.about.com/od/chemistryglossary/a/pressuredef.htm
4. Serway and Beichner Physics for Scientists and Engineers 5th Edition. 2000. p. 471. 

Winter Ice Melt Palooza!

Learn why salt helps to melt ice using different types of salt. 


Appropriate Age Level

5+ (some concepts can be 3+)

Science Learned
Freezing Point - The temperature at which a liquid becomes a solid
Temperature - a physical measurement of the hotness or coolness of something
Freezing Point depression - when the freezing point of something is lowered by a solute
Colligative Property - a property of a substance that depends on the number of particles present instead of type of particle.
Solution - a homogeneous mixture of solute and solvent that is in one phase (liquid, solid, gas)
Solvent - A substance that dissolves a solute.
Solute - A substance, usually a solid, dissolved into another substance, usually a liquid. 
Liquid- a state of matter that is characterized by taking up a definite volume but having no particular shape
Solid - state of matter that is characterized by being structurally rigid and resistance to change

Materials Needed
Essential:
Ice Block
Table Salt - NaCl
Optional:
Magnesium Chloride MgCl2
Calcium Chloride CaCl2
Thermometer

Experiment
1. Either find a block of ice outside, or freeze some water in a plastic container. 

2. Explain how ice is frozen water and a solid and how its freezing point is at 32F or 0C.  When water is not frozen it is in the liquid state. 

3. On a surface that you don't mind getting wet, take some table salt and add it to the block of ice in one area. Attempt to stir in the salt into the ice.  Notice how the salt, the solute, melts the ice, the solvent. It essentially lowers its freezing point of the ice.  (If the student wants to know more, it essentially breaks the hydrogen bonds required to keep the ice in solid form by the salt molecules coming in and wanting to share the same space and transferring electrons.)

4. If you have Magnesium Chloride and/or Calcium Chloride on hand you can add a spoonful of each to other parts of the block.  (You could probably add some different food colorings to differentiate the different materials if you would like more wow!) If you have a thermometer on hand you can check out the differences in temperature of the solution melts.  The MgCl2 will depress the freezing point of ice to 5F.  While table salt only depresses it until 15F. Calcium chloride depresses it until -20F. While if you are doing this experiment inside the temperatures gotten will not be at these exact levels you should be able to see some difference. 

5.  Explain that the differences of the freezing points arrise from freezing point depression being a colligative property and the differences in size of the molecules, where NaCl is the smallest, CaCl2 is the largest, makes a difference in melt points. 

Time Allotted
20 minutes

References
http://chemistry.about.com/od/solutionsmixtures/a/freezingpointde.-Nxc.htm
http://chemistry.about.com/od/howthingsworkfaqs/f/how-does-salt-melt-ice.htm
http://en.wikipedia.org/wiki/Colligative_properties

Grow tomatoes, grow!

 Grow some tomato plants to later plant outside and learn about germination and photosynthesis in the process.

Appropriate Age Level

3+ for the actual experiment

5+ for concepts


Materials Needed
Dirt
Planting pot(s) or plastic cups
Tomato seeds
Water
Time
Camera to take growth pictures with

Science Concepts Learned

Germination (1) - (see picture below) the process where a seed grows to become a seedling. For a seed to do this it needs water, oxygen and to be at certain temperature. 

1.The root emerges through the seed.

2.The part of the seed called the hypocotyl pushes it way out of the soil.

3.The hypocotyl straightens itself out.

4.Leaves begin to form.


Photosynthesis -  (see photo below) the process where plants convert energy from light from the sun into chemical energy that can be used by the plant.  

The reaction is the following (3):

                                light

carbon dioxide + water  ------->    sugar + oxygen 


Activity/Experiment

1. Set out cups or pots and fill the pots with dirt (a starter mix for plants is recommended) as many as you want though think about seed crowding.  

2. Plant tomato seeds 1/4 inch deep in the dirt (2).

3. Water the seed/dirt mixture to make it soggy but not swampy.

4. In 5 to 10 days germination should occur. Take a picture of the potted seeds each day in this range and discuss the germination steps listed above in the terms section. 

5. After germination has occurred, weekly take pictures of the plants.  

6. After a few weeks compare the size of the plants with the pictures taken and from them you can talk about photosynthesis and how the light and water has helped the plant to grow. 

7. Continue growing the plants, and you can either transfer them to larger pots and keep them inside or you can transfer them outside if it is the right time of year. 

8. Enjoy the fruit you get from this practical example of science!


Time Allotted 

5-10 minutes weekly

References: 

1. http://www.cactus-art.biz/note-book/Dictionary/Dictionary_G/dictionary_germination.htm
2. http://www.colostate.edu/Depts/CoopExt/4DMG/VegFruit/tomatind.htm
3. http://en.wikipedia.org/wiki/Photosynthesis