Video Transcript
The table shows the properties of
five different metals. (a) Which metal is most suitable
for use in aircraft bodies? And the answer options are (A)
metal a, (B) metal b, (C) metal c, (D) metal d, or (E) metal e.
The properties of different metals
listed in the table are strength, malleability, corrosion resistance, and
density. Cost is not really a property of a
metal but is a factor that a company will consider when fabricating a specific metal
part. The properties of metals determine
how useful they are in different applications. Note that the pure form of a metal
is often not used for applications. Usually metals are used in
alloys. And the properties of the metals in
the alloy determine the overall properties of the alloy.
The question asks which metal is
most suitable for use in aircraft bodies. When making an aircraft body, a
manufacturer would want to make it lightweight and relatively strong. These two factors of strength and
density are arguably the two most important factors when making an aircraft
body. Of the five given metals — a, b, c,
d, and e — the one with the lowest density also has a moderate strength. These properties or characteristics
would be useful for use in aircraft bodies. Metals a, b, c, and e have high,
very high, or moderate density. They would not be suitable to make
an aircraft body from because the body would not be lightweight. So the metal most suitable for use
in aircraft bodies is metal d. Also, metal d is highly malleable
and corrosion resistant. It can be molded into an aircraft
body shape easily and would have a long lifespan.
(b) Which metal is most suitable
for use in mass-produced gates and railings? And the answer options are the same
as before.
When mass-producing a product, cost
is often an important factor. In most cases but not always, a
company will plan to produce a product at low cost but sell many units and thus make
a good profit overall. When making gates and railings
whose purpose is for security, strength is the most important factor, so strength
and cost are arguably the most important considerations when mass-producing gates
and railings. The most suitable metals from those
in the table with a high strength and a low cost are metals a and b. Both could be suitable to make
gates and railings.
To decide between the two, we’d
need to know the relative cost of each, but we don’t have this information. b has a
high strength, although not as high as a, and also has a high malleability. This means metal b will be easier
to press into shape. This is particularly important if
the gates and railings are made from flat panels pressed and cut into shape, making
metal b cost less overall to make, compared to metal a which is less malleable. So the metal most suitable for
mass-produced gates and railings is metal b.
Part (c) which metal is most
suitable for use in hip replacements? And the answer options are the same
as before.
What properties would an artificial
hip joint need to have? Well, strength would be important
to carry the weight of the body as well as corrosion resistance because the new hip
joint would be constantly surrounded by bodily fluids as well as dissolved
oxygen. Malleability is an undesirable
property for a hip joint replacement. We would not want the weight of the
body to deform or alter the shape of the hip joint replacement. So we’re looking for a metal with a
high strength, a high corrosion resistance, and a low malleability. It would be really great if the
cost of hip replacement were low. However, this type of replacement
only occurs maybe once in the lifetime of a person. And so a high cost is not really an
influencing factor here.
Metals a, b, and e all display high
or very high strength. However, we can rule out metals a
and b because they have a low corrosion resistance, while metal e has a very high
corrosion resistance and a very high strength. Added to that, it has a low
malleability. And although the cost is high, the
part would have a long lifespan. So the metal most suitable for use
in hip replacements is metal e.
