INTERNATIONAL AND SPECIALIZED TRANSPORT
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JULY 2013
35
THE KNOWLEDGE
be a tension of 500 N in the rope. Newton
has put an end to this belief with his third
“action = −reaction” law. To create a tension
of 500 N in the rope, both people have
to pull with a force of 500 N in opposite
directions.
How is this applicable in our industry?
When a load is suspended from a crane
hook, this load exerts a force onto the
boom tip of that crane. At the same time
the boom tip (via hydraulic cylinders and/
or pendant ropes) exerts the same force
onto the load that prevents it from falling
down. Assuming that the load measures
500 N, then this is the force exerted onto
the boom as well as onto the load.
Archimedes of Syracuse
Widely known as just Archimedes,
Archimedes of Syracuse (287 – 212 BC)
was a Greek mathematician, physicist,
engineer, inventor and astronomer. He left
ARCHIMEDES OF SYRACUSE’S DEFINITION OF BUOYANCY
Density of boat
Gravity
Buoyancy
Density of water
us with the principle of the lever, a crane
in its most basic form. He is also credited
with the foundations of hydrostatics. In
particular, buoyancy is important in our
industry for ships and barges. For every
voyage, lift-on, lift-off, roll-on and roll-off,
the buoyancy is monitored as it keeps the
ship or barge afloat.
Buoyancy is defined as the upward
force exerted on a submerged object,
by the liquid it is submerged in, equal
to the weight of the liquid that the
object displaced.
According to Newton’s third law,
there should be another (downward)
force at play as “action = −reaction”. This
is indeed the case, the other force is the
gravitational force, the buoyancy and
gravitational forces are equal in magnitude
and opposite in direction.
With these three laws of Newton and
the hydrostatic and buoyancy laws of
Archimedes under your belt, you are able to
understand the forces that play on an object
being transported or lifted by land or sea
or both.
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Archimedes is credited with the principle of
the lever – a crane in its most basic form
INDUSTRIE COMETTO S.p.A.
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TEL. +39.0171.263300
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building for the heaviest duties
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