1. Unit 4 – Density and Pressure
Chapter 11 in the textbook
Unit 4 – Density and Pressure

2. Density and Pressure
On your whiteboards, write down any words you think are related to density and pressure. No books or devices. (5 minutes)

3. Lesson aims:
To discover the meaning and application of density.

4. Which one weighs more?
Which one has a greater volume?
1kg of  Or

5. 1kg of coal = 1kg of feathers =

6. How can you explain this relationship?
Try to write a sentence on your WB describing this relationship between mass and volume.

7. What is DENSITY?
You have found a mysterious metal block buried in your garden… IS IT TREASURE?!

8. How do we know?
Consider ways that we can establish what metal we have found… No book or devices. (10 minutes)

9. Every substance has a specific DENSITY…
REVIEW: Describe the pattern of density for elements down a group in the periodic table.

10. Every substance has a specific DENSITY…
First, what is density?
Finding the Density of Water
What is the volume of 50ml of water?
What is the mass of 50ml of water?
What is mass/volume?

11. So… What is Density? = m d m3 kg mass g v / cm3 units kg density
volume d m3 kg
mass g v /
cm3
units kg

12. DEFINITION a matter DENSITY the for unit in a is amount of volume
Density is the amount of matter in a certain volume of a substance.
amount
substance of
volume

13. DEFINITION a matter DENSITY the for unit in a is amount of volume
Density is the amount of matter in a certain volume of a substance.
amount
substance of
volume
DENSITY is the amount of matter in a unit volume for a substance.

14. Floating rocks??

15. Every substance has a specific DENSITY…
So how are you going to find out what your substance is??

16. Find the density of your metal
Procedure for Finding Density Before starting, write a procedure on your WB, then when approved, copy into your NBs. Then, START!

17. Some common metal densities:
Chemical Symbol
Density (g/cm3)
Aluminium Al
2.70
Iron Fe
7.87
Copper Cu
8.96
Silver Ag
10.5
Lead Pb
11.3
Gold Au
19.3
Platinum Pt
21.5

18. Density simulation:

19. Density of Liquids
What is the density of water?

20. If we poured some liquids into the same container, what will happen?
Water
Honey
Cooking oil
Ethanol (alcohol)
Find the density of these 4 liquids.
Predict the order they will settle.

21. Backs to the Boards
Explain the word to one student (who has their backs to the board)… First person to hold up the correct word wins the point.

22. MASS

23. DENSITY

24. LIQUID

25. VOLUME

26. kg

27. cm3

28. Archimedes Principal
Who came up with the concept of density?

29. Density game…

30. Density
Finish these statements about density on your WBs: Density is… Density = Density units are =

31. PRESSURE
Lesson aims: To listen to Queen a lot…

32. PRESSURE
Lesson aims: To understand what affects pressure. HOMEWORK!!! Bring an (empty) drinks can on Monday…

33. How would you feel about sleeping on this?

34. POPPING BALLOONS!!
How easy is it to pop a balloon with nails?

35. Now you try…
1 balloon per group. Try and pop the balloon using the nails you receive. In your notes, describe what you did and what happened (mention the single nail and the nail bed).

36. Popping a Balloon with nails
First, Ms Lee popped a balloon very easily with a single nail. Then I tried with the bed of nails (81 nails) and I could push quite hard without the balloon popping.

37. Bed of nails?

38. Speed Reading…
Read pages 106 and 107 = 3 minutes.

39. Question Notes Questions in one colour, Notes in another.
Write on the WBs.

40. What is pressure?
The concentration of a force: Large force + small area = high pressure Large force + large area = small pressure

41. How do we calculate pressure?
Complete this example: P=F/A = 10/1 = 10 Ncm-2 = 10/0.004 = 2,500 Ncm-2

42. Name 3 things which require a HIGH PRESSURE.
Why?

43. Name 3 things which require a LOW PRESSURE
Why?

44. Which would create more pressure?
An elephant’s foot, or a woman in stilettos?
Use device to find the answer!
(show your working…)

45. Pressure consolidation
Select the INDIGO activity….

46. REVIEW
2 minutes to discuss each of the following slides:

47. Why do you think my feet are wide?

48. Why are snow shoes used for walking in really deep snow?

49. My skis are flat at the bottom to stop me sinking but they also have a sharp edge to dig into hard snow. Explain how these 2 uses of my skis work.

50. Why are ice skate blades
sharp?

51. Why are dart tips pointed?

52. Why does a sharp knife cut better
than a blunt knife?

53. Pressure in Liquids and gases
Lesson aims: To understand how liquids and gases exert pressure.

54. States of Matter and Pressure
REVIEW – Draw the particles in a SOLID, LIQUID and GAS.

55. States of Matter and Pressure
Where are these substances exerting a pressure?

56. Pressure in LIQUIDS
Predict what will happen if 3 holes are punctured in this water bottle. How far will the water come out?

57. WHY. Discuss in your groups… Now find out on page 108-109
WHY? Discuss in your groups… Now find out on page (Write on WBs)

58. All the water at the top is exerting pressure on water below it.
Therefore, the water at the bottom experiences the highest pressure.

59. Design a dam.
How are you going to keep all this water from bursting through the dam? Explain why it is this shape.

60. Pressure in Liquids and gases
Lesson aims: To understand how liquids and gases exert pressure.

61. GO!!! Air Pressure QUESTION: Why does a balloon keep its shape?
I need 5 volunteers!
You are gas molecules, and the people around you are the sides of a balloon.
GAS MOLECULES – you will move randomly around inside the balloon.
GO!!!

62. Inside a balloon…
What is air pressure? What affects air pressure?

63. What will happen…
Predict what will happen to the air pressure in the following situations.

64. If the amount of gas doubles (volume stays the same)
If the amount of gas doubles (volume stays the same). The pressure doubles! There are twice as many collisions with the sides of the container.

65. If the volume of the container increases. The air pressure decreases
If the volume of the container increases. The air pressure decreases. There is more space for the gas, so the number of collisions decreases.

66. If the temperature of the gas drops. The pressure also drops
If the temperature of the gas drops. The pressure also drops. The gas particles have less energy, which means they move more slowly and so there are fewer collisions with the sides of the container.

67. Now these:
The amount of gas decreases. The temperature rises. The volume of the container decreases. (Discuss in your groups).

68. Can we use air to crush a can?
DISCUSS!

69. Can we use air to crush a can?
Clean your can!
Pour 15 mL of water into your can.
Heat over the Bunsen burner (until the water has nearly boiled away).
Turn upside down into water.

70. AMAZING AIR PRESSURE!
Homework. Describe and explain!