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5. Mechanisms
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6.
ENERGY ACCUMULATION MECHANISMS
We sometimes need mechanisms
that can absorb
20
, accumulate
21
or
dissipate
22
the energy that they receive.
For example, shock absorbers of carbs
absorb energy that can cause damage
or discomfort. They make driving easier
on bumpy roads. Other mechanisms,
such as watch springs, accumulate
energy that can be used later.
6.1.
Accumulation: springs
Springs are flexible devices that absorb energy when we apply force to them. Then
we can release
23
the energy in a controlled way. We use springs with different shapes
for various purposes.
❚❚
We push on
compression springs
. We find these springs in sofas.
❚❚
We pull on
traction springs
. We find them in metallic bed frames.
❚❚
We bend
torsion springs
. We see these springs in clothes pins.
Analyse
36.
Look at the images of the springs above. Notice their shapes. Can you
imagine what type of force we use with these springs? Where can we
see springs like these?
Analyse
39.
Look at the springs of
the bicycle seat. How do
they work? What type
of force is applied to
them? Some bicycle seats
have shock absorbers
instead of springs. What
are the advantages of
each system?
Applications
:
there are often springs in sofas, beds, industrial and domestic
machines, spring-operated pens, watches, clocks and toys.
6.2.
Dissipation: suspension systems
Car suspension systems are useful because they absorb and dissipate motion when
the road is bumpy. This makes driving more comfortable.
❚❚
Shock absorbers
are usually made with spiral steel springs.
❚❚
Leaf springs
are made with long, curved pieces of steel of different lengths
placed on top of each other and joined in the middle.
Analyse
37.
There are springs in some pens that we use for writing. Why are they
useful? How do we operate these springs? What type of force do we
apply to them?
Apply
38.
Make a list of objects that have compression springs, traction springs
and torsion springs. How do you apply force to these objects?
ENERGY ACCUMULATION
MECHANISMS
Some devices have springs
that accumulate energy and
release it slowly. In the past,
watches had springs sopeople
had to wind them every day.
Today, most watches use
batteries. Some new watches
accumulate energy from our
body movements.
20
absorb
:
take in, reduce the effect of
21
accumulate
: gather gradually and keep
22
adissipate
: disperse or spread gradually
23
release
:
set free or let go
There are two types of energy
absorption mechanisms:
❚
those that accumulate energy
like springs.
❚
those that absorb and
dissipate energy like shock
absorbers or suspension.
Key concept
ADVANCE EDITION
