# Problem Solving - Substances from the Earth by 33z50F

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```									                                                 Problem Solving – Particles (D)

1.      “U” values are used to compare the insulation properties of materials.
Roof insulation, for example, can be bought in different thicknesses with different “U” values.
30 mm thick insulation has a “U” value of 0.15, whereas insulation 50 mm thick has a “U value of 0.11.
A “U” value of 0.08 is given to insulation which is 80 mm thick.

Complete this table.

Thickness of insulation (mm)                                     “U” value

2.      This is part of an index of a book.

Air pollution                          20                  Headlights                           31
Anti-roll bars                         19                  Insurance                            3
Brakes                                 37                  Radiators                            27
Carburettors                           39                  Safety                               15
Exhausts                -corrosion     43                  Seat belts                           16
-gases         17                  Sidelights                           30
-types         42                  tyres                 -pressure      26
Gear boxes                             50                                        -types         25

a) Which two pages should Joanna look up to find out about anti-roll bars and safety?

Pages ……… and …………

b) Joanna also looked up pages 17 and 20.
What was she trying to find out about?

………………………………………………………………………………………………………………………

3.      Read the passage and then answer the questions.

Farmers have always fought a battle against weeds, which compete with crop plants. Instead of
weeding by hand, most farmers now use weed-killing chemicals called herbicides. Unfortunately,
herbicides also kill many wild flowers. As a result, many wild flowers are extinct or very rare.
Herbicides have helped to remove weeds and reduce food shortages across the world. However, the
absence of the colour and beauty of wild flowers is a great loss to the environment.

a) Give one advantage and one disadvantage of using herbicides.

………………………………………………………………………………………………………………………

….………………………………………………………………………………………………………………….

b) What is a herbicide?

………………………………………………………………………………………………………………………

WAID ACADEMY PROBLEM SOLVING PARTICLES TOPIC             LEVEL D                                   page 1        June 2005
4.      The weights of different metals used by a factory in one month are shown in the table.

Metal            Weight (tonnes)

Aluminium               12
Copper                   7
Zinc                     4

a) Use the information in the table to complete the bar graph:

Weight
(tonnes)

4

2

0
aluminium

Metal

b) 25% of the aluminium is used to make wheels.
What weight of aluminium is this?

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