Hello scientists!
In this UNIT 1, we'll study the matter, its properties, how we measure things, kind of substances, and a lot of interesting things.
Remember, everything in the Universe is MATTER or ENERGY.
1. The properties of the matter.
How do we recognise the matter?
Matter has three properties:
- Matter occupies space, it has VOLUME.
- Matter attracts matter, it has GRAVITY.
- Matter tends to move if it is in motion or to keep stopped if it is still, it has INERTIA.
The MASS is the amount of matter.
More mass -> More gravity and more inertia.
Less mass - > Less gravity and less inertia.
The WEIGHT is the effect of gravity.
Gravity causes Weight
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An objects weight is how hard gravity is pulling on it.
We think the weight is the same everywhere ... because we all live on the surface of the planet Earth!
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But in orbit it would not push on the scales at all.
The scales would show 0 kg ... but the mass is still 100 kg !
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An object's mass doesn't change (unless you remove some!), but its weight can change.
So Why Do People Say Weight instead of Mass?
People often use "weight" to mean "mass", and vice versa.
Because gravity is pretty much the same everywhere on Earth, we don't notice a difference.
But remember .. they do not mean the same thing,
and they can have different measurements.
Here are some conditions where the Weight might change:
- in space (can be weightless!)
- on the moon (a 100 kg mass would weigh 16.6 kg)
- you can even get very slight differences in weight in different locations on earth!
2. The measure.
When we measure, we compare a property of the matter, called MAGNITUDE, with a known and universal unit.
We can measure differents magnitudes, using different units.
In the past, each country had its own units. Luckyly, all scientist agreed to have the same units, and they created the International System of Units (abbreviated SI from French: Le système international d'unités).
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| British Units |
HOW CAN WE CONVERT UNITS?
Remember the multiples and submultiples:
- Kilo... k-
- Hecta...h-
- Deca...da-
- ----- ----
- deci...d-
- centi...c-
- mili....m-
LENGTH: The S.I. Unit is the metre.
Example: 754,56 cm -> hm
We go up (divide) 4 steps, so we move left the comma 4 places:
754,56 cm = 0,075 456 hm
SURFACE: The S.I. Unit is the square metre.
Example: 125,75 dam2 -> dm2
We go down (multiply) 2 steps, each step multiply 100, so we move right the comma 4 places:
125,75 dam2 = 1 257 500 dm2
VOLUME: The S.I. Unit is the cubic metre.
Example 1: 250 000 mm3 -> m3
We go up (divide) 3 steps, each step multiply 1000, so we move left the comma 9 places:
250 000 mm3 = 0,000 250 m3
Example 2: 5,25 litres -> cm3
One litre is equal to one dm3, so we go down (multiply) 1 step, each step multiply 1000, so we move right the comma 3 places:
5,25 litres = 5,25 dm3 = 5 250 cm3
MASS: The S.I. Unit is the kilogram. We also use the metric TON (T), 1 Ton = 1000 kg.
Example: 4 250 mg -> g
We go up (divide) 3 steps, so we move left the comma 3 places:
4 250 mg = 4,25 g
DENSITY:
The density of a substance is its mass divided its volume:
The S.I. is kilogram / cubic metre (kg/m3).
In the following tables you can check the density of different substances, in g/cm3.
LET'S PRACTICE!
1) You can practice unit conversions, completing the following sheet (it is corrected during the class):
- Click here to download the sheet.
2) Practical exercises:
3) CAMP NOU OR SANTIAGO BERNABEU?
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| Camp nou field dimensions |
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| Santiago Bernabeu field dimensions |
Complete on your notebook:
Camp Nou
Long:__________ . Wide: __________ . Surface: ___________
Santiago Bernabeu
Long:__________ . Wide: __________ . Surface: ___________
Which field has more surface?
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