Term 3 Revision Test Answers

1. Base SI Units

metre (m) measures length

kilogram (kg) measures mass

second (s) measures time

Kelvin (K) measures temperature

Ampere (A) measures electrical current

candela (cd) measures light intensity

mole (mol.) measures amount of substance

2. Base SI Units are the original seven units decided upon in Paris. Derived SI Units are units that come from the Base Units, and can be made in two different ways. Firstly, I could add a prefix to a Base SI Unit to create a derived unit (millimetre), or I may combine base units to make a derived unit. (e.g. metres per second).

3. Error of parallax – can be avoided by keeping my eye perpendicular to the point I’m measuring.

Zero Error – I can make sure that I begin measuring from zero.

Worn away Ruler – I can measure from another mark, but must subtract that point from what I’m measuring.

4. A = l x b

= 20 metres x 8 metres

= 160 square metres

The pool has a surface area of 160 square metres.

5. V = l x b x h

= 20 metres x 8 metres x 20 decimetres

= 200 decimeters x 80 decimetres x 20 decimeters

= 320 000 cubic decimetres

As 1 cubic decimetre = 1 litres, 320 000 cubic decimetres = 320 ooo litres.

6. Absolute Zero is the coldest possible temperature, and is also the point where an object has no energy.

7. Absolute Zero on the Celcius (centigrade) scale is – 273 degrees Celcius (centigrade)

8. Scientists use Kelvin rather than Celcius (centigrade) scale because we know ice has a temperature, and in the real world you cannot get less than nothing.

9. a) weight = mass x gravity’s pull

= 48 kg x 10 N

= 480 N

Dennis’ weight is 480 Newtons.

b) Dennis’ mass on Earth is 48 kilograms.

c) weight = mass x gravity’s pull

= 48 kg x 1,667 N
= 80,016 N

Dennis’ weight on the Moon is 80,016 Newtons.

d) Dennis’ mass on the Moon is 48 kilograms.