Ch. 18 Air & WaterI. O2 and CO2 Cycle1. The air is made up of nitrogen, oxygen, carbon dioxide, water vapour and other gases.2. O2 and CO2 cycle is the constant exchange of O2 and CO2 among living things.3. O2 and CO2 cycle is important to living things because they need a constant supply of oxygen and carbon dioxide in the air to survive.4. Living things need oxygen and water to stay alive. They also give out carbon dioxide. 5. Due to the oxygen and carbon dioxide cycle, the oxygen in the air never runs out. 6. During photosynthesis, living things produced and release O2 into the air. 7. During respiration, living things give out CO2. It is also released into the air when living things die and decay or when man burns oil or fossil fuels.8. In a daytime, plants take in CO2 and give out O2 during photosynthesis. But at night, they take in oxygen and give out carbon dioxide.

II. Water Cycle9. The continuous movement of water from earth, to the sky and back to the earth is called water cycle_.10. In the water cycle, the movement of water requires the heat from the sun to take place.11. There are two processes that occur in water cycle, evaporation and condensation. 12. Evaporation is the change of water from liquid to a gas. 13. The change of state of water from a gas to a liquid is called condensation.14. The process of water cycle starts when the water evaporate into the air and rise into the sky, then it condenses to form a droplet of water, when the droplets of water get too big and heavy it falls into the earth as rain. 15. In the evaporation process only the pure water rises into the sky. When it falls back to the earth as rain, it purifies and helps to cool the air. 16. Human activities have caused great _harm to our environment that affect the water cycle.17. Those two activities that affect water cycle are deforestation_ and _burning___ of _fossil fuels.18. Deforestation is the clearing of forest by __cutting________ or __burning________ trees for woods or land.19. Deforestation will increase the rainfall and it will cause more _floods_________ and ___landslildes___ in some places, while less rainfall causes __drought________.20. Burning of fossil fuels produce harmful gases that form __acid_______ when it __mix_______ with water.21. Because of burning fossil fuels, the earth gets _replenished____ with acidic water instead of _freshwater_ when it rains.22. The period of time without rain is called __drought_______________.23. Global warming is the __increase_______________ in the earths temperature.24. The large amount of earth sliding down is called landslides__.

Ch.19 Gravitational and Frictional ForcesI. Gravitational force1. The force between things and the earth that pulls the thing close to the ground is gravitational force2. Gravitational forces pull all things down, towards the centre of the earth.3. The earth exerts a gravitational force on the moon that makes the moon orbit around the earth.4. Gravitational force allows us to stand on the ground and not float away.5. More effect of gravitational force are, it speeds the skiers as they skies downhill, it pulls the swimmer down towards the water, it cause water to fall downwards and it pulls the climbers back down as they climb.6. Gravitational force between objects and earth is called weight.7. The gravitational force becomes weaker as we move away from earth, thats why the astronaut is floating in the space because there is very little gravitational force pulling them to the ground8. Weight is a force and it can be measured by spring balance.9. Unlike weight, mass is not a force. It is constant wherever the object is.10. Even mass is not a force, it still can be measured.

II. Frictional force1. The force that opposes motion is called frictional force; this frictional force can be a pull or a push.2. Some effect s of frictional motion is: to slow down and stop the moving object, to prevent object from starting to move, to affect the movement of an object on different surfaces.3. A toy car moving on the table can be stop because there is the frictional force that acts in the direction opposite to the direction of the motion of toy car. 4. Smooth surface allows the object to move faster than a rough surface because it gives less frictional force.5. Friction also produce heat by rubbing the surface of each objects6. Not only frictional force occurs between two objects, it also produced when objects move through air and water.7. The frictional force that slows objects down as they move through air is called air resistance, while the one that slows objects down as they move through water is called water resistance.8. The amount of air resistance acting on an object depends on many factors such as shape.9. Racing car is designed with a shape that allows air to move over smoothly to reduce air resistance.10. Water resistance pushes against a moving object and slows it down as it move through the water.11. It is hard to walk through water in a swimming pool because water resistance slowing down our movement.12. In our daily life, frictional force between the soles of our shoes and the ground stop us from slipping when we walk. 13. The tread patterns on the tyres increase the frictional force between tyres and the ground, it allows vehicle to stay on the road.14. In an ancient time people make fire by rubbing hard wooden stick on a piece of soft wood that generate heat.15. We can grip things better because there is fine ridge pattern on our finger.16. Frictional force can be both useful and cause problems in our daily life.17. Friction cause object to slowdown, overheat and wear out. 18. In order to overcome the problem cause by friction we can reduce the friction between surfaces with lubricant and rollers/wheels.19. For the overheat problem, we can apply lubricant on the moving part of machine, and to move heavy objects easily we can use rollers and wheels.20. Lubricant is materials used to make surface slippery to reduce friction.Ch. 18 Air & WaterIII. O2 and CO2 Cycle25. The air is made up of __________, _______________, ___________ ___________, ____________ ________ and _____________ ______________.26. O2 and CO2 CYCLE is the constant exchange of O2 and CO2 among the __________ __________.27. O2 and CO2 cycle is important to living things because they need a _____________ supply of ______________ and __________ __________ in the air to ________________.28. Living things need _______________ and _______________ to stay alive. They also _________ _______ carbon dioxide. 29. Due to the ________________ and _________ __________ cycle, the _______________ in the air never ______ ______. 30. During photosynthesis, living things produced and ___________ O2 into the air. 31. During respiration, living things ___________ ________ CO2. It is also released into the air when living things _________ and___________ or when man burns _________or _________ __________.32. In a daytime, plants ____________ __________ CO2 and __________ _________ O2 during photosynthesis. But at night, they take in ___________ and give out ________ _____________.

IV. Water Cycle33. The continuous movement of water from earth, to the sky and ___________ to the earth is called ___________.34. In the water cycle, the movement of water ___________ the ____________ from the sun to take place.35. There are two processes that occur in water cycle, evaporation and _________________. 36. Evaporation is the change of _________ from____________ to a gas. 37. The change of state of water from a _________________ to a liquid is called condensation.38. The process of water cycle starts when the water ___________ into the air and rise into the sky, then it condenses to form a ___________ of water, when the droplets of water get too big and heavy it _________________ into the earth as _________________. 39. In the evaporation process only the pure water rises into the sky. When it falls back to the earth as rain, it ______________ and helps to _________ the air. 40. Human activities have caused _______ _______ to our environment that affect the water cycle.41. Those two activities that affect water cycle are _________________ and ___________ of _________ ________.42. Deforestation is the clearing of forest by _________________ or _________________ trees for woods or land.43. Deforestation will increase the rainfall and it will cause more _________________ and _________________ in some places, while less rainfall causes _________________.44. Burning of fossil fuels produce harmful gases that form _________________ when it _________________ with water.45. Because of burning fossil fuels, the earth gets ________________ with acidic water instead of _________________ when it rains.46. The period of time without rain is called _________________.47. Global warming is the _________________ in the earths temperature.48. When the large amount of earth sliding down it means _________________.

Ch.19 Gravitational and Frictional ForcesIII. Gravitational force11. The force between __________ and _____ __________ that pulls the thing close to the ground is gravitational force12. Gravitational forces pull all things down, __________ the center of the earth.13. The earth exerts a gravitational force on the moon that makes the moon __________ __________ the earth.14. Gravitational force allows us to stand on the ground and not __________ away.15. More effect of gravitational force are, it speeds the skiers as they __________ __________ , it pulls the swimmer down towards the water, it cause water to fall ___________________ _ and it pulls the climbers back down as they climb.16. Gravitational force between __________ and __________ is called weight.17. The gravitational force __________ __________ as we move away from earth, thats why the astronaut is floating in the space because there is __________ __________ gravitational force pulling them to the ground18. Weight is a force and it can be measured by __________ __________ .19. Unlike weight, mass is __________ _______ __________ . It is constant wherever the object is.20. Even mass is not a force, it still can be _______________.

IV. Frictional force21. The force that _______________ motion is called frictional force; this frictional force can be a ________ or a _________.22. Some effect s of frictional motion is: to ________ _______ and stop the moving objects, to ____________object from starting to move, to affect the movement of an object on different _____________.23. A toy car moving on the table can be stop because there is the _______________ _______________ that acts in the direction opposite to the direction of the motion of toy car. 24. _______________ surface allows the object to move faster than a rough surface because it gives less frictional force.25. Friction also produce heat by _______________ the surface of each objects***26. Not only frictional force occurs between two objects, it also produced when objects move through air and water.27. The frictional force that slows objects down as they move through air is called air ___________, while the one that _______________objects down as they move through water is called water resistance.28. The amount of air resistance acting on an object depends on many factors such as _______________.29. Racing car is designed with a shape that allows air to move over smoothly to _______________ air resistance.30. Water resistance ____________ __________ a moving object and slows it down as it move through the water.31. It is ___________ to walk through water in a swimming pool because water resistance slowing down our movement.32. In our daily life, frictional force between the _______________ of our shoes and the ground stop us from _______________when we walk. 33. The tread patterns on the tyres _______________ the frictional force between tyres and the ground, it allows vehicle to stay on the road.34. In an ancient time people make fire by rubbing hard wooden stick on a piece of soft wood that _______________ _______________.35. We can _______________ things better because there is fine ridge pattern on our finger.36. Frictional force can be both useful and _______________ _______________ in our daily life.37. Friction cause object to _______________, _______________ and wear out. 38. In order to overcome the problem cause by friction we can reduce the friction between surfaces with _______________ and rollers/wheels.39. For the overheat problem, we can apply lubricant on the moving part of machine, and to move _______________ _______________ easily we can use rollers and wheels.40. Lubricant is materials used to make surface _______________ to reduce friction.