Science Fair Project 1

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Got Salt?

Comparisons of back bay salt content to tide cycles

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    Categories

• Environmental Science

• Earth Science

• Chemistry

Purpose or Problem

Comparing salt content in back bay water during high tides and low tides.tide, plants and animals living there would have to be tolerant of these changes.

Hypothesis

Hypothesize that a noticeable difference will occur in the salt content in back bay water depending on the cycle of the tide (high tide, low tide).

Materials’ List

• Access to an inlet and bay areas that experience tidal changes, fed by an ocean or a large body of salt water
• Four wide-mouth jars (peanut butter, pickle, or other food containers) of equal  size
• Masking tape
• Pen or marker
• About two weeks of waiting time
• Several small twigs
• A sunny window
• Tide chart helpful, but optional
• Possible adult supervision needed

Procedure

The amount of water gathered for each sample and the location the samples are taken from remain constant. The tide cycle is the variable. For this project, you must have access to an inlet and a back bay that receives tidal flows from an ocean or a large body of salt water. When you work around water, make safety your number one concern. Know how to swim, wear a life preserver, and always have a friend or an adult accompany you. Gather four clear glass or plastic jars that have wide mouths. Jars of this type include 16- or 18-ounce peanut butter, pickle, or sauce containers. All four jars must be identical. Place a strip of masking tape on each jar and label each one as to the location and tidal

status that identifies the water sample they will contain. You need to determine the time of high and low tides. Tide tables are often found in local marinas, newspapers, or by listening to a National Oceanic and Atmospheric Administration (NOAA) weather station (weather radios can be purchased at many consumer electronic stores). If you do not have access to a tide table, you can spend a day making note of where the high- and lowtide levels are along bulkheads or other land markings. Throwing a small twig in the water at an inlet and watching the direction it floats tells you whether the tide is flowing in or receding out. The figure on the top of the next page shows two points where you should collect water samples: one is located in a back bay area, and the other is at the mouth of the inlet, where the bay meets the ocean. When the tide is just beginning to flow in (just past the time of low tide), fill a jar with water from Point A and one from Point B. Secure lids on the jars to keep the water from spilling as you transport them home.

Later, when the tide is just beginning to recede (just past the time of high tide), fill a jar with water from Point A and one from Point B. [Optional: If you have access to two inlets that feed back bay areas, you can enhance your project by collecting additional samples at points shown in the figure below.]

When you get home, place the jars in a warm, sunny window and remove the lids. It takes about two weeks for all the water to evaporate. You can decrease evaporation time by placing them in an area of increased heat, such as near a heat duct or in an oven at a low temperature. Do not place the jars directly on a stove burner, as the jars are not designed to be exposed to high temperatures.When all the water has evaporated, screw the lids on again to prevent any further contamination and to keep the contents intact. Do you see chunks of salt in the jars? Salts are crystals, and one of the characteristics of crystals is their unique shapes. Do the chunks have shapes characteristic of crystals? You may also want to examine the salt chunk sunder a magnifying glass or microscope.

Results

Write down the results of your experiment.

Document all observations and data

collected.

Conclusion

Come to a conclusion as to whether or not

your hypothesis was correct.

Wind funnel, Science Project

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Wind funnel

Light a candle and blow at it hard through a funnel held with its mouth a little way from the flame. You cannot blow out the flame; on the contrary it moves towards the funnel. When you blow through the funnel the air pressure inside is reduced, and so the air outside enters the space through the mouth. The blow air sweeps along the funnel walls: if you hold the funnel with the edge directly in front of the flame, it goes out. If you blow the candle through the mouth of the funnel, the air is compressed in the narrow spout, and extinguishes the flame immediately on exit.

Floating card, Science Project

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Floating card

Many physical experiments seem like magic, but there are logical explanations and laws for all the strange occurrences. Stick a thumbtack through the middle of a halved postcard. Hold it under a cotton spool so that the pin projects into the hole and blow hard down the hole. If you manage to loosen the card, you really expect into fall. In fact, it remains hovering under the spool. Bernoulli’s law explains this surprising result. The air current goes through at high speed between the card and the spool, producing a lower pressure, and the normal air pressure pushes the card from below against the spool. The ascent of an aeroplane takes place in a similar manner. The air flows over the arched upper surface of the wings faster than over the flat under-surface, and therefore the air pressure above the wings is reduced.

Flying coin, Science Project

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Flying coin

Lay a sixpence or a dime four inches from the edge of the table and place a shallow dish eight: inches beyond it. How can you blow the coin into the dish! You will never do it if you blow at the coin from the front - on the false assumption that the air will be blown under the coin because of the unevenness of the table and lift it up. It will only be transferred to the dish if you blow once sharply about two inches horizontally above it. The air pressure above the coin is reduced, the surrounding air, which is at normal pressure, flows in from  all directions and lifts the coin. It goes into the air current and spins into the dish.

Trapped ball, Science Project

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Trapped ball

Place a table tennis ball in a funnel, hold it with the mouth sloping upwards, and blow as hard as you can through the spout. You would hardly believe it, but nobody can manage to blow the ball

out. The air current does not hit the ball, as one would assume, with its full force. It separates and pushes through the places where the ball rests on the funnel. At these points the air pressure is lowered according to Bernoulli’s law, and the external air pressure pushes the ball firmly into the mouth of the funnel.

Wind-proof coin, Science Project

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Wind-proof coin

Push three pins into the middle of a piece of wood and lay a coin (5 new pence or 25-cents) on top of them. You can make a bet! Nobody who does not know the experiment will be able to blow the coin off the tripod. The metal cannot hold the gust of air on its narrow, smooth edges. The gust shoots through under the coin and reduces the air pressure, forcing the coin more firmly on to the pins. But if you lay your chin on the wood just in front of the coin and blow with your lower lip pushed forward, the air hits the underside of the coin directly and lifts it off.

Bernoulli was right, Science Project

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Bernoulli was right

Lay a postcard bent lengthways on the table. You would certainly think that it would be easy to overturn the card if you blew hard underneath it. Try it! However hard you blow, the card will not rise from the table. On the contrary, it clings more firmly. Daniel Bernoulli, a Swiss scientist of the eighteenth century, discovered that the pressure of a gas is lower at higher speed. The air stream produces a lower pressure under the card, so that the normal air pressure above presses the card on to the table.

Curious air currents, Science Project

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Curious air currents

If you stand behind a tree trunk or a round pillar on a windy day, you will notice that if offers no protection, and a lighted match will be extinguished. A small experiment at home will confirm this: blow hard against a bottle which has a burning candle standing behind it, and the flame goes out at once. The air current divides on hitting the bottle, clings to the sides, and joins up again behind the bottle with its strength hardly reduced. It forms an eddy which hits the flame. You can put out a lighted candle placed behind two bottles in this way, if you have a good blow.

Egg blowing, Science Project

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Egg blowing

Place two porcelain egg-cups one in front of the other, with an egg in the front one. Blow hard from above on to the edge of the filled cup. Suddenly the egg rises, turns upside down and falls into the empty cup. Because the egg shell is rough, it does nor lie flat against the smooth wall of the egg-cup. Air is blown through the gap into the space under the egg, where it becomes compressed. When the pressure of the cushion is great enough, it lifts the egg upwards.

Compressed air rocket, Science Project

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Compressed air rocket

Bore a hole through the cap of a plastic bottle, push a plastic drinking straw through it and seal the joints with adhesive. This is the launching pad. Make the rocket from a four-inch-long straw,

which must slide smoothly over the plastic straw. Stick coloured paper triangles for the tail unit at one end of the straw, and at the other end plasticine as the head. Now push the plastic tube into

the rocket until its tip sticks lightly into the plasticine. If you press hard on the bottle the projectile will fly a distance of 10 yards or more. When you press the plastic bottle, the air inside is compressed. When the pressure is great enough, the plastic straw is released from the plug of plasticine, the released air expands again, and shoots off the projectile. The plasticine has the same function as the discharge mechanism in an airgun.