Do now!
Can you complete any
unfinished calculations from
last lesson??
Last lesson
Calculating density
Density
Remember that density is the mass of one cubic centimetre (or sometime cubic metre) of a substance.
So for example, gold has a density of 19.3 g/cm3. His means one cubic centimetre (cm3) of gold has a mass of 19.3 grams.
Density = mass
volume
Or using the formula triangle;
m
D x V
g/cm3
g
cm3
The formula!
Density of regular shapes
volume = length x width x height
density = mass/volume
mass using a scale
lengthwidth
height
Density of liquids
Mass of liquid and cylinder
Mass of cylinder
Mass of liquid
Density = mass/volume
Volume
Density of irregular shapes (1)
Difference in level gives the volume of the shape
mass
Density = mass/volume
Density of irregular shapes (2)
Displacement can
volume of object
mass
Density = mass/volume
I’m worried!
I’m worried!
Some more density questions. Homework due for 8th September
(Tuesday)
This lesson
• Recall and use the relationship between pressure, force and area
Oh no!
http://wm-od.cdn.turner.com/cnn/big/bestoftv/2007/04/06/roberts.the.shot.cnn.ws.wmv
Spread the force over a greater area
Camels
Snow shoes
Tom
Caterpillar tracks
House foundations
Sharp?
I had a dream
Death?
Drawing pins
Pressure
Pressure = Force
AreaN/m2 or Pa
N
m2
Pressure
Pressure = Force
AreaN/m2 or Pa
N
m2
F
AP x
Can you copy this please?
An example
A woman of weight 600N has a shoe area of 150 cm2 and a man of weight 750 N has a shoe area of 360 cm2. What is the pressure beneath their feet?
An example
A woman of weight 600N has a shoe area of 150 cm2 and a man of weight 750 N has a shoe area of 360 cm2. What is the pressure beneath their feet?
Angelina pressure = force/area = 600/150 = 4 N/cm2
Brad pressure = force/area = 750/360 = 2.1 N/cm2
Let’s try some questions!
Page 63, questions 1 to 4.
Can you then write (and answer) 3 questions of
your own?
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