Mechanical advantage is a measure of the force amplification
achieved by using a tool, mechanical device or machine system. Ideally,
the device preserves the input power and simply trades off forces
against movement to obtain a desired amplification in the output force.
The model for this is the <span>law of the lever.</span> Machine components designed to manage forces and movement in this way are called mechanisms.
An ideal mechanism transmits power without adding to or subtracting
from it. This means the ideal mechanism does not include a power source,
and is frictionless and constructed from rigid bodies that do not
deflect or wear. The performance of a real system relative to this ideal
is expressed in terms of efficiency factors that take into account
friction, deformation and wear.
Gravitational forces are stronger over shorter distances, and
weaker over longer distances. That's a big part of the reason
why our bodies are attracted to the Earth with more force than
we're attracted to Jupiter, for example.
The force doesn't just get weaker in proportion to the distance.
It gets weaker in proportion to the SQUARE of the distance.
Exercise 8. Compare the meanings of these verbs.
Came out - came, left - came, brought - drove, looked -
looked, drove - drove away, said - told.
The continental shelf, continental slope, and continental rise combine to form the <span>continental margin</span><span>.
</span>The continental shelf is the portion of the land mass that extends into ocean water.
Continental slope begins where the continental shelf ends. It does exactly what its name implies and serves as a boundary between the oceanic crust and the continental crust.
The continental slope divides the continental and oceanic crusts. Over a period of time, soil, rocks, and debris wash down the steep sides of a continental slope due to the influence of gravity. They pile up at the bottom of the slope and form a small ridge called continental rise.
