Page 45 - @ccess 2 Reader´s Book

Practice 6 A WELL-OILED MACHINE

Academic and educational environment
SOCIAL LANGUAGE PRACTICE: Paraphrase information to explain the operation
mechanism of a machine.
Article from Nasa 's
webpage

HOW DOES IT WORK?
aircraft (n.):
aeronave
What Is a Helicopter? planeador
glider (n.):

A helicopter is a type of aircraft that uses rotating or
spinning wings called blades to fly. Unlike an airplane
or glider, a helicopter has wings that move.

Unlike a balloon, a helicopter is heavier than air and uses an
engine to fly. A helicopter's rotating blades, or rotor, allow it
to do things an airplane cannot.

How Does A Helicopter Work? lift (n.):
empuje

In order to fly, an object must
have "lift", a force moving it
upward. Lift is usually made by
wings. Wings create lift because
of a relationship called the
Bernoulli Principle.

The Bernoulli Principle
describes how the speed of air
and the pressure in the air are
related. When the speed goes
up, the pressure goes down and the opposite is also true.

Wings are curved on top and flatter on the bottom. This
shape is called an airfoil. That shape makes air flow over the
top faster than under the bottom.

44 Reader's Book