Properties of Air

1. Properties of Air

2. Vocabulary Gas: one of the three states of matter Oxygen: gas necessary for life Insulating: Protecting against loss of heat Compressed: pushed to fit the same mass in a smaller space Mass: a measurement of matter

3. Air Air is not just one thing; it has many “ingredients”. Nitrogen (78%), a gas, is air’s main ingredient. Oxygen (21%) is another important ingredient, though there is much less of it than nitrogen. Many other gases, including carbon dioxide, make up about 1% of air. One ingredient varies in its amount: the water vapour content of air depends on many factors occurring in the atmosphere. Without water vapour, we would not have clouds or rain.

4. Properties of Air Understanding the properties of air allows us to understand its abilities and possibilities. There are 7 properties – like one for every day of the week! 1. Air takes up space 2. Air has weight 3. Air pushes on objects 4.Air resists things moving through it 5. Air has an insulating property 6. Air expands when heated 7. Air can be compressed

5. Air takes up Space How can we prove this? Try to have air take up space that is occupied by something else.

6. Experiment

7. Air has Weight Take an object that can be inflated or deflated. Compare their equivalent weights in their two states. Is there a difference? In class example – balloon scale!

8. Air Pushes on Objects

9. Air Resists Things Moving Through It

10. Air has an Insulating Property Gases posses poor thermal conduction properties compared to liquids and solids and thus makes a good insulation material if they can be trapped. In order to further augment the effectiveness of a gas (such as air) it may be disrupted into small cells which cannot effectively transfer heat by natural convection. Think of your winter jackets - are they dense or puffy?

11. Air Expands when Heated Have you ever noticed that a ball or swim floaty that you used one hot summer day is deflated the next morning? This is due to this property of air.

12. Air Can be Compressed

13. Hot Air Rises • You know that warm air rises because it is lighter than cool air. When do we see this in real life? • Floor display freezers – the cool air of the freezer stays in the freezer because it is much heavier than the warm air around it. • Portable heater – A heater is best on the floor, since heat rises. Warm air rises and will not sink below where the heater is placed.

14. Forces of Flight Chicken Run Inside Out Four Forces of Flight 1. Thrust: the force that causes forward movement 2. Drag: the force that resists movement 3. Lift: the force that causes an object to rise 4. Gravity: the force that pulls objects to the Earth

15. Movement Through Air Birds and airplanes have special designs to help them fly, take off, land, or even turn in the air. The four forces of flight can be altered to achieve different movements in the air. Streamlined: shape of an object that reduces drag, as it provides the least air resistance. Pitch: climb or descend Roll: turn over Yaw: turn to the left or right

16. Bernoulli’s Principle David Bernoulli, a scientist, proposed that changes in air speed are related to changes in air pressure, faster moving air exerts lower pressure than slower moving air. An airplane’s wings take advantage of this principle. The top surface of a wing is curved and the end of the wing is lower than its front ede. The air above the wing travels faster over a curved surface than the air below the wing. The slower air has higher pressure than the faster air, and it is this pressure difference that generates lift.

17. Airfoil A wing’s special shape is called an airfoil. Many other objects, both natural and human-made, share this shape in order to generate lift or move through air.

18. Lift and Thrust Propeller planes, jet planes, and helicopters all have different methods of generating thrust and lift. A propeller plane has a propeller that spins, making air flow faster in front of it than behind it; faster moving air equals lower air pressure, and the plane moves forward.

19. Lift and Thrust A jet plane, on the other hand, has jet engines into which air flows. The air is mixed with fuel inside the engines and ignited. The resulting exploding gas travels out of the engine, thrusting the plane forward. For both propeller and jet planes, it is this forward motion that forces air to flow over the wings fast enough to generate lift.

20. Lift and Thrust A helicopter’s rotors generate both lift and thrust. The main rotor rotates with such speed that air flows fast enough over the rotor’s blades to generate lift, allowing the helicopter to take off vertically, unlike planes, which need a runway. The rotor is adjustable, and this is what provides thrust.

21. Lift and Thrust The tail rotor keeps the helicopter’s fuselage from rotating with the main rotor and also works in much the same way as the main rotor to generate lift and thrust.

22. Living Things and Flight • Most birds, insects, and even some mammals can fly. • Some important vocabulary – • Adaptation: a change to better suit an environment • Predator: an animal that hunts for food • Prey: an animal that is hunted for food • Ascend: move upward (into the air)

23. Living Things in Flight Some plants’ seeds float like balloons, or rotor down like helicopters. What are the possible advantages of this seed formation?

24. Living Things and Flight When we consider bird adaptations, what are the possible causes behind the adaptations they have?

25. Living Things and Flight Consider the claws that certain birds have? What is the purpose of this adaptation?

26. Living Things and Flight What is the purpose of the peacock’s tail feather adaptation?

27. Living Things and Flight Why does the humming bird fly the way it does?

28. Living Things and Flight When geese fly together, each goose provides additional lift and reduces air resistance for the goose flying behind it. By flying together, the whole flock can fly approximately 70% farther on the same amount of energy. This allows them to migrate more efficiently

29. Living Things and Flight • Characteristics of flying birds • Wings to produce lift • Powerful flight muscles to generate forward motion • Aerodynamic body reduces drag • Very light bones with air sacs reduces weight • Gliding and Parachuting • Other flying animals

30. A History of Aviation Kite flying is the earliest form of man-made flight – dating back several hundred years BCE

31. History of Aviation Leonardo da Vinci contemplated flight in the 15th century. He made several designs though never implemented any of the designs

32. History of Aviation • In the 18th century, hydrogen gas was discovered and the hydrogen balloon was invented. • At the same time, the Montgolfier brothers began manned flights of the hot air balloon • Originally King Louis XVI had decreed condemned criminals would be the first pilots • Instead, two gentlemen petitioned for the honour • They drifted 8 km powered by wood fire

33. History of Aviation • Non-steerable balloons we employed during the American Civil War. • Ferdinand von Zeppelin flew as a balloon passenger in 1863. (First developed in 1899)

34. History of Aviation In 1891, Otto Lilienthal used an A-frame glider, the Derwitzer, for a total of 5 hours of flying time. In August of 1896, Otto’s glider stalled and he was unable to regain control. Falling from 15m, he broke his neck and died the next day.

35. History of Aviation The Wright brothers (1903), Orville and Wilbur are generally credited with inventing, building and flying the world’s first successful airplane (in a heavier-than-air aircraft) – including a control that allowed them to steer and maintain equilibrium

36. History of Aviation The first seaplane was flown in 1910. The creator was Henri Fabre from France.

37. History of Aviation Although there were many other attempts to create helicopters, the world’s first practical helicopter was designed by Heinrich Focke and flew in 1936.

38. History of Aviation Once flight within the Earth’s atmosphere had been attained, the next obvious focus was beyond Space exploration and travel began to be investigated, leading to the first man to orbit the Earth – Yuri Gagarin; and a few years later, the first man to walk on the moon – Neil Armstrong

39. History of Aviation • Advances in aero-dynamics and technology have continued to lead to greater improvements in design and flight ability. • Flying around the world without refueling or landing • Drag reduction • UAV’s habeing used in modern warfare • Solar-powered plane • Drones

40. Project: Airplane • Howard Hughes • As Howard Hughes did in the clip, consider the factors that impact flight and design an airplane • The airplane should attempt the following two goals: • Longest sustained flight • Greatest distance travelled in the air