HOMEWORK:
1. Check
the solutions to the exercises you
did last week from the books of N.S. (Student´s Book and Activity
Book).
UNIT 6 Natural Science – MACHINES AND ENERGY
4º NS STUDENT´S
BOOK (solutions)
PAGE 83
SOLUTIONS
1 Simple machines – screw, saw, garden shears, retractable
tape measure, scraper, saw.
2 Screws are used for holding materials together.
3 Simple machines work in opposition to natural forces;
They are often powered by human physical energy.
4 Electricity from various sources such as wind, the
Sun, coal, gas, petroleum, water, etc.
5 Pupils’ own answers.
6 Pupils’ own answers.
7 Screw, wedge, gas, helmets, goggles.
PAGE 84
SOLUTIONS
1 a.false; b.true; c.false; d.true; e.true.
PAGES 86, 87
SOLUTIONS
1 A table; a screw; It holds the table legs in place.
2 Pupils’ own answers.
3 – 1 lever, stapler – class; 2 lever, scissors –
class; 3 lever, door handle – class; 4 lever, human arm – class.
4 Galileo’s experiment with an inclined plane demonstrated
that as an object travels down the plane due to the force of gravity, it
travels progressively faster. He developed the theory that simple machines do
not create energy, they transform it. He identified five classical simple machines.
PAGES 88, 89
SOLUTIONS
1 Pupils’ own answers.
2 Pupils’ own answers.
3 Radiator – thermal machine; calculator – information
processing machine; motorbike – mechanical machine; computer – information processing
machine; freezer – thermal machine.
4 Skateboard – human physical energy; car – oil, gas,
or electricity; surfboard – water energy; sailing boat – wind energy.
5 A power saw; special gloves and goggles; to protect
her skin or eyes against small pieces of wood.
4º NS ACTIVITY
BOOK (solutions)
PAGE 32
SOLUTIONS
1 – SIMPLE machines:
inclined plane, wedge, pulley, screw, wheel and axle, lever.
COMPLEX machines:
mechanical machines, thermal machines, information processing machines.
2 – Answers. 2. Effort
– 3. Simple – 4. People – 5. Energy – 6. Load – 7. Pulley.
PAGE 33
SOLUTIONS
3 – a. screw – b.
wheel and axle – c. wedge – d. inclined plane – e. pulley – f. lever.
4 – Answers: You can
use an inclined plane to move objects from one level to another. – The round
shape of the wheel reduces the amount of friction. – The axle is in the centre
of a wheel. – You can use a wedge to cut or to hold objects in place. – A wedge
is made up of two inclined planes together. – You can use a screw to tighten or
join objects together.
5 – Archimedes.
PAGE 34
SOLUTIONS
6 – Answers :
CLASS 1 LEVER: a.
effort – b. fulcrum – c. load – Examples: A seesaw and a crowbar.
CLASS 2 LEVER: a.
fulcrum – b. load – c. effort – Examples: A wheelbarrow and a nutcracker.
CLASS 3 LEVER: a. fulcrum
– b. effort – c. load – Examples: A hockey stick and a stapler.
7 – a. mechanical
machine – b. information processing machine – c. thermal machine.
PAGE 35
SOLUTIONS
8 – a. oil (WRONG)
people (CORRECT) – b. harder (WRONG) easier (CORRECT) – c. thermal (WRONG)
mechanical (CORRECT) – d. mechanical (WRONG) thermal (CORRECT) – e. heaters
(WRONG) computers (CORRECT) – f. force (WRONG) motion (CORRECT)
9 – a. gas or oil – b.
the Sun – c. people – d. wind
10 – Student´s own
answers. Examples: a. Do not run with them in your hands. – b. Do not use it
near water.
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