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?