A simple machine is a mechanical
device that changes the direction or
magnitude of a force. In general, they
can be defined as the simplest
mechanisms that use mechanical
advantage (also called leverage) to
multiply force. Usually the term refers
to the six classical simple machines
which were defined by Renaissance
scientists.
Lever
A lever is a solid bar that rotates, or turns
around a fixed point. The bar can be straight or
curved. The fixed point is called the fulcrum. The
heavy object that has to be moved or lifted is
called the load.
Levers can help lift a heavy weight with much
less effort.
The wheel and axle is generally considered to be a wheel
attached to an axle so that these two parts rotate
together in which a force is transferred from one to the
other. In this configuration a hinge, or bearing, supports
the rotation of the axle.
A pulley is a wheel on an axle or
shaft that is designed to support
movement and change of direction
of a cable or belt along its
circumference. Pulleys are used in a
variety of ways to lift loads, apply
forces, and to transmit power. In
nautical contexts, the assembly of
wheel, axle, and supporting shell is
referred to as a "block."
An inclined plane, also known as a ramp, is a flat supporting
surface tilted at an angle, with one end higher than the other,
used as an aid for raising or lowering a load. Inclined planes
are widely used to move heavy loads over vertical obstacles;
examples vary from a ramp used to load goods into a truck, to
a person walking up a pedestrian ramp, to an automobile or
railroad train climbing a grade.
A wedge is a triangular shaped tool, and is a
portable inclined plane. It can be used to
separate two objects or portions of an object,
lift up an object, or hold an object in place. It
functions by converting a force applied to its
blunt end into forces perpendicular (normal)
to its inclined surfaces. The mechanical
advantage of a wedge is given by the ratio of
the length of its slope to its width. Although a
short wedge with a wide angle may do a job
faster, it requires more force than a long
wedge with a narrow angle.
By: Mariam and Rami
Grade 6