Physical Science Section 3.1 Matter and Energy

1. Physical Science Section 3.1 Matter and Energy

2. 1. The physical form of matter is known as its state. It is determined partly by how the substance’s particles move.

3. 2. Matter is made of atoms and molecules that are always in motion. The higher the temperature, the faster the particles move. At the same temperature, particles with more mass move more slowly than less massive ones. All these statements are part of the kinetic theory of matter.

4. 3. Particles of a solid do not move fast enough to overcome the strong attraction between them, so they vibrate in place. They can be represented by a “picture” like this:

6. 3. Cont. Solids have a definite shape and volume because of the strong attractions between the particles.

7. 4. Particles of a liquid move fast enough to overcome some of the forces of attraction between them. The particles are able to slide past one another. They can be represented by a “picture” like this:

8. 4. Cont. Because the particles are free to move, liquids flow freely and take the shape of their containers.. They do not easily change volume; the volume of the liquid remains constant. NOTE: The particles of a liquid are not as spread out as most people think. The particles are actually quite close together, but they are not organized.

9. 5. Particles of a gas move fast enough to overcome nearly all of the forces of attraction between them. The particles move independently of one another. They can be represented by a “picture” like this:

10. 5. Cont. They do not have fixed shapes, and their volume can also change. This is because the particles move fast enough to break away from each other.The gas expands to fill the space it is in. Gases can be compressed because their particles can be pressed closer together by pressure.

11. 6. Liquids and gases are both fluids because their particles can move freely past each other (they can flow.)

12. 7. The sun and other stars are made of plasma. About 99% of the universe is in this state, so it is the most abundant state of matter. Particles in plasma are electrically charged, or ionized. It is defined as being free-moving ions and electrons.

13. 7. Cont. In addition to being present in the stars, plasma is found naturally in lightning, fire, and aurora borealis. This is a glow in the upper atmosphere caused by the collision of high energy plasma with gas particles.

14. 7. Cont. When electric current is passed through gases plasmas are formed artificially. Gases do not conduct electric current, but plasmas do.

15. Plasma TV’s contain a layer of xenon and neon that start to glow when electricity runs through them.

16. 8. Because all particles of matter are in constant motion (even if they only vibrate), they have kinetic energy. Temperature is a measure of the average kinetic energy of the particles in an object. The faster the particles move, the higher their kinetic energy, and the higher their temperature.

17. 8. Cont. Temperature is not determined by how much of the substance you have. 2oC 2oC

18. 9. The total kinetic energy (thermal energy) DOES depend on the number of particles present. More coffee = more total thermal energy

19. 10. Water can undergo multiple changes of state. Some of these changes requireenergy, and some release energy. GAS sublimation condensation evaporation melting freezing SOLID LIQUID

20. 11. Ice, liquid water, and steam all have different amounts of energy, but they are all the same substance, with the chemical formula H2O. During a change of state, the temperature does not change, but its energydoes change. 0oC

21. 12. The melting point of a solid is the temperature at which it changes from a solid to a liquid. As it is heated, the particles vibrate faster as they gain energy, and eventually they break away from their fixed positions, and the solid melts. Melting point also depends on pressure.

22. 13. Evaporation is defined as the change of state of a substance from a liquid to a gas. Evaporation from the surface only; lower molecules are still liquid.

23. 13. Cont. If this happens throughout the entire liquid at a specific temperature and pressure, it is called boiling. The temperature at which this happens is called the boiling point of that substance. Boiling throughout the entire liquid at its boiling point

24. Some solids, such as dry ice, change directly from a solid to a gas, in a process called sublimation. This also happens to ice cubes in a freezer, as they change directly to avapor.

25. 14.The opposite can also occur, as when water vapor forms frost on the ground or on a very cold window.

26. 115.Sublimation, melting, and boiling all require energy.

27. 16. Condensation, the change of state from a gas to a liquid, is the opposite of evaporation. Energy is released (given off) as the particles slow down and come together.

28. 17.The change of state from a liquid to a solid is called freezing. It is the opposite of melting, and it releases energy as the particles slow down and line up in a pattern. Freezing and melting occur at the same temperature.

29. 18. During a change of state, the temperature does not change until the entire change is complete.

30. 19. Mass is conserved for all physical and chemical changes. The mass of all substances after a change is the same as the mass of all substances before the change.

31. 19. Cont This is known as the law of Conservation of Mass. Mass cannot be created or destroyed.

32. 20. Energy can change form but the total amount of energy present before and after the change is the same

33. 20. Cont • This is known as the law of conservation of energy.

34. 20 Cont • Energy cannot be created nor destroyed. Sometimes energy is transferred to the surroundings as heat

35. Section 3

36. 21. Liquids and gases are classified as fluids. They exert pressure evenly in all directions. The unit of pressure is the pascal, and it can be calculated with this equation: pressure = force/area or P = F/A

37. 22. Pressure inside a tire is caused by the force of air particles inside tire; the more air you pump into the tire, the greater the number of air particles pushing against the inside, and the greater the pressure is.

38. 23. The SI unit of pressure is the pascal, abbreviated Pa. It is equal to a force of one Newton exerted over an area of one square meter.

39. 24. A water bed that weighs 1050 N covers an area of 3.65 m2 on the floor. How much pressure does it exert on the floor? Given: Unknown: Equation: P = F/A Math: Answer:

40. 25. In a container of fluid, pressure increases with depth. Therefore, the forces pushing up on an object in the fluid are greater than the forces pushing it down. The resulting upward force is called buoyant force. All fluids exert an upward buoyant force on matter.

41. 26. If an object is completely submerged in a fluid, the water displaced equals the buoyant force acting on an object. This concept is known as Archimedes’ Principal. If the weight of the object is greater than the buoyant force, the object will sink. If the weight of the object is less than the buoyant force, the object will float.

42. 27. You can determine whether a substance will float or sink by comparing its density to that of the fluid. The density of a brick is about 2 g/cm3, and the density of water is 1.00 g/cm3, so the brick sinks in water. Helium is about 1/7 as dense as air, so helium floats in air.

43. 28. A rock weighs 25 N. It displaces a volume of water that weighs 15 N. What is the buoyant force on the rock? 15N

44. 29. Most fish have an organ called a swim bladder, which the fish can fill with gases. If the swim bladder is inflated, the fish’s volume is increased, and its density is decreased. This keeps the fish from decreased. Sharks do not have swim bladders so they must swim constantly to keep from sinking.

45. 30. Steel is about 8 times as dense as water, so a block of steel would sink. A ship, however, floats because it has a hollow shape, which increases its volume. The mass does not change, so this decreases the ship’s density, and it floats.

46. 31. When you apply pressure to any part of a tube of toothpaste, toothpaste usually comes out the end, because pressure is transmitted throughout the toothpaste.

47. Con’t This demonstrates Pascal’s principle, which states that a change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of the fluid.

48. 32. Hydraulic devices use liquids to transmit pressure from one point to another. A small downward force is applied to a small area, and it transmits pressure to a larger area, creating a larger force.

49. cont The plunger where the small force is applied travels a greater distance than the heavy load on the smaller area travels

50. 33. Given: F1 = 160 N A1 = 0.5 cm2 A2 = 3 cm2 Unknown: F2 = ? Equation: F1 = F2 A1 A2 Math: 160 N/0.5 cm2 = F/3 cm2 Answer: 960 N