Up, Up, and Away Air and Aerodynamics Flight AIR AND AERODYNAMICS TOPIC A Describe the properties of air and the interactions of air with objects in flight. SLE #1 PROVIDE EVIDENCE THAT AIR TAKES UP SPACE AND EXERTS PRESSURE, AND IDENTIFY EXAMPLES OF THESE PROPERTIES IN EVERYDAY APPLICATIONS PROPERTIES • Air has mass We saw that when a balloon is filled with air, it is heavier than when it is deflated. • Air takes up space In our experiments, we observed that a jar that looked empty was actually full of air because it kept the water from easily entering the jar through the funnel. If there was another hole in the stopper, the water went in easily as the air had somewhere to go. We also see evidence of air when we blow up a balloon, inside bike and car tires, turn on a fan, and when we breathe. • Air exerts pressure We covered a ruler on the table with the newspaper and then we tried to lift the paper off the table by hitting the end of the ruler but the weight of the air pressing down on the newspaper did not let the paper move. The pressure of air is about one kg per square cm. That means your open hand is actually holding up about 50 kg of air! Air can also hold up a glass of water upside down when you cover it with a piece of cardboard. • Air has the power to hold things up • Air is invisible We looked inside a box but we couldn’t see anything. After, we found out that air is everywhere and although we can’t see it, we can feel it when we move our hands and see evidence of it when leaves blow or a flag moves. • Air can be compressed We used the plungers to compress air. Our Air Experiments • Air is Everywhere – (Funnel, jar, plasticine, coloured water) Air has the power to hold things up. • Fill It Up Please – (Two flasks, funnels, one hole stopper, two hole stopper, water, beaker) Air has the power to hold things up. • Diving Paper – (Bowl, beaker, water, paper) Air has the power to hold things up. • Huff N’ Puff – (Balloon, pop bottle) Air takes up space - A-Weigh We Go – Air has mass/weight. - Drinking Straws (Straws, glass, water) - Crushing Air (Water bottle, hot water, cold water) – Warming the bottle caused the air to expand – some air left the bottle. When we cooled it, the air inside condensed. The air pressure inside was lower and the air pressure outside the bottle was cooler and heavier (higher air pressure), so it pushed the bottle and crushed it. SLE #2 PROVIDE EVIDENCE THAT AIR TAKES UP SPACE AND EXERTS PRESSURE, AND IDENTIFY EXAMPLES OF THESE PROPERTIES IN EVERYDAY APPLICATIONS. Air is fluid and is capable of being compressed Expt. – Taking the Plunge – We covered the plunger with our finger and tried to compress the air into a smaller area. It got harder to push as the air got more compressed. Gas particles are quite far apart and can be compressed (squeezed closer together to occupy a smaller volume) by applying pressure. Balloon Rockets • We learned that when blowing up a balloon, you are squeezing or compressing the air inside of it. When you let the balloon go, the air is forced out through the neck. This force pushes the balloon in the opposite direction. • Everyday uses of compressed air: tire pumps, ball pumps, paintball guns, lungs, pressurized water pump in our houses, nail guns, jack hammers, oxygen tank, air compressors Adjust the Volume • We used pop bottles, hot and cold water, thermometers, and balloons. The amount of air in the bottle stayed the same. The water surrounding the bottles changed the air temperature in the bottles causing the air to expand and contract. The hot air expanded and needed more space causing the balloon to inflate. The cold air condensed (taking up less space), and the balloon deflated. A thermometer works on this same principle. The Great Squirt Challenge As we blew into the tubing, we compressed the air in the flask by adding more air. This increased the air pressure in the flask. Due to compression, the water was forced out of the medicine dropper nozzle. When the air in the flask could not be compressed anymore, the water was forced up the tube. SLE #3 DESCRIBE AND DEMONSTRATE INSTANCES IN WHICH AIR MOVEMENT ACROSS A SURFACE RESULTS IN LIFT – BERNOULLI’S PRINCIPLE. • Air movement across a surface results in lift …. Bernoulli’s Principle •Blow over the top of a strip of paper and it will rise. — Bernoulli’s principle Our Experiments Let It Shine – candle, straw, jar, lid, plasticine (The air moving around the can is at a lower pressure than the still air. This low pressure moving air is pushed quickly around the can towards the flame by the still air – high pressure.) Ball in a Funnel – We held the funnel upright and put a ping pong ball in it. We blew on the stem of the funnel. We couldn’t blow the ball out because the air moving around the ball is moving faster than the surrounding air. The moving air created a low pressure area and the higher pressure of the surrounding air pushed against the ball and kept it in the funnel. Lift Off – We blew over a piece of folded and taped paper. The fast moving air created an air of pressure lower than the air that moved more slowly. The paper was forced up by higher atmospheric pressure known as LIFT. The Fastest Spray in the West – We cut a straw in half and put one half in a glass of water. With the other half, we blew into it across the other piece of straw. The higher pressure of the atmosphere pushed down on the surface of the water forcing the water up the straw toward the lower pressure created by the fast moving air at the top. When the water rose to the mouth of the straw, it was sprayed away in the stream of fast moving air. Paint sprayers work this way. SLE #4 RECOGNIZE THAT IN ORDER FOR DEVICES OR LIVING THINGS TO FLY, THEY MUST HAVE SUFFICIENT LIFT TO OVERCOME THE DOWNWARD FORCE OF GRAVITY. Bird and bats have movable wings that change shape during flight to maximize efficiency. Some insects have very thin strong wings that beat very fast - over 400 times a second for mosquitoes. • In order for devices or living things to fly, they must have sufficient lift to overcome the downward force of gravity. 1. If lift becomes greater than mass, the plane ascends. 2. If thrust becomes greater than drag, the plane goes faster. 3. If lift, mass, thrust, and drag become equal, the plane would hover … would maintain the same speed and the same altitude (theoretically). 4. If thrust becomes less than drag, the plane slows down. 5. If lift becomes less than mass, the plane descends. LIFT THRUST DRAG WEIGHT SLE #5 & #6 IDENTIFY ADAPTATIONS THAT ENABLE BIRDS AND INSECTS TO FLY. DESCRIBE THE MEANS OF PROPULSION FOR FLYING ANIMALS AND FOR AIRCRAFT. Identify adaptations that enable birds and insects to fly. Wings – The wings are connected to powerful chest muscles. The wings are curved on top and are almost flat on the bottom. This shape gives lift as the bird flies through the air. Feathers – The stiff flight feathers on the wings are hollow and light and their shaft is not centered so that they overlap. The shaft of the feather is made of a tough materials called keratin making the feather stiff but flexible. Skeleton – Bones are hollow or partially hollow making them light but strong. Muscles – Large pectoral muscles generate the power to flap the wings. Muscles do not tire quickly. Breathing system – Lungs are connected to a network of air sacks that fill up with air helping to provide the body with a large amount of oxygen used during flight. Propulsion: Birds use their legs and wings to take off. Airplanes have jet engines or propellers to help them take off. • Birds and insects flap wings and use thermal rising air to fly. • Flying squirrels glide down, not fly. • Planes push air backward over fixed wings with prop or jet engine. SLE #7 RECOGNIZE THAT STREAMLINING REDUCES DRAG, AND PREDICT THE EFFECTS OF SPECIFIC DESIGN CHANGES ON THE DRAG OF A MODEL AIRCRAFT OR AIRCRAFT COMPONENTS. • Streamlining reduces drag •The part that catches on the air causes drag. •Put a hand out window of a fast moving car and experiment with the different hand shapes. Oxidation of Alanna’s apple SLE #8 RECOGNIZE THAT AIR IS COMPOSED OF DIFFERENT GASES, AND IDENTIFY EVIDENCE FOR DIFFERENT GASES. EXAMPLE EVIDENCE MIGHT INCLUDE: EFFECTS ON FLAMES, THE ‘USING UP’ OF A PARTICULAR GAS BY BURNING OR RUSTING, ANIMAL NEEDS FOR AIR EXCHANGE. Fire needs oxygen to burn. Blowing CO2 into clear lime water turns it milky-looking. Rusting of the steel wool used up 1/5 of the oxygen. Carbon Dioxide put out the flame. Carbon Dioxide is heavier than air. • Air is composed of different gases. Nitrogen 78.09% Oxygen 20.9% Argon 0.93% CO2 +other gases 0.042% Our experiments 1. Fruity Oxidation – Oxygen in the air reacts with the chemicals on the surface of an object. The oxygen replaces other substances. The clue to the presence of oxygen is a brownish colour. To stop fruit from rapid oxidation: leave the peel on, refrigerate it, cover the fruit in ascorbic acid like lemon juice, and/or cover with plastic wrap 2. Gone to Rust – We put wet steel wool in the top of a test tube and then inverted it into a beaker of water. After one day, some of the steel wool was rusted and about 1/5 of the test tube had water in it. Rusting uses up oxygen and our air is about 1/5 oxygen so once the oxygen was used up, no more rusting took place. Paint, oil, grease, galvanizing (covering with zinc metal) are effective ways of protecting iron. How does an airplane take off? 1 • When an aircraft moves into the wind, the wings cut the airflow in half. • Some air travels above the wing, some air travels below the wing. • Plane wings are build to be curved on top and flat on the bottom. How does an airplane take off? 2 • The wind, or air stream, flowing over the wing travels a different path from air traveling under the wing. • This difference in the path of the wind, creates lower air pressure above the wing. The higher air pressure under the wing lifts the plane into the air creating lift. How does an airplane take off? 3 • When there is enough lift to overcome gravity, the plane takes off. • All the time, the plane is being slowed down by having to push through the air. • This is called drag, and the engines have to overcome it. How does an airplane take off? 4 • As long as the plane continues to move forward at a fast enough speed, the plane continues to fly. • Planes use engines to move quickly down the runway to create the lift for take off. • Helicopters rotate their wings (or blades). The rotating motion forces air past the wings creating lift.