3. WHAT IS SIMPLE MACHINES?
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.
4. LEVER
A lever (/ˈliːvər/ or US /ˈlɛvər/) is a machine consisting
of a beam or rigid rod pivoted at a fixed hinge, or fulcrum.
A lever is a rigid body capable of rotating on a point on itself.
On the basis of the location of fulcrum, load and
effort, the lever is divided into three types. It is one of the six
simple machines identified by Renaissance scientists. A lever
amplifies an input force to provide a greater output force,
which is said to provide leverage. The ratio of the output force to
the input force is the mechanical advantage of the lever.
7. INCLINED PLANE
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.[1][2][3] The inclined
plane is one of the six classical simple machines defined by Renaissance scientists. 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.[3]
Moving an object up an inclined plane requires less force than lifting it straight up, at a cost of
an increase in the distance moved.[4] The mechanical advantage of an inclined plane, the factor
by which the force is reduced, is equal to the ratio of the length of the sloped surface to the
height it spans.[5] Due to conservation of energy, the same amount of mechanical energy (work)
is required to lift a given object by a given vertical distance, disregarding losses from friction,
but the inclined plane allows the same work to be done with a smaller force exerted over a
greater distance.[6][7]
The angle of friction,[8] also sometimes called the angle of repose,[9] is the maximum angle at
which a load can rest motionless on an inclined plane due to friction, without sliding down.
This angle is equal to the arctangent of the coefficient of static friction us between the
surfaces.[9]
Two other simple machines are often considered to be derived from the inclined
plane.[10] The wedge can be considered a moving inclined plane or two inclined planes
connected at the base.[6] The screw consists of a narrow inclined plane wrapped around
a cylinder.[6]
The term may also refer to a specific implementation; a straight ramp cut into a steep hillside
for transporting goods up and down the hill. It may include cars on rails or pulled up by a cable
system; a funicular or cable railway, such as the Johnstown Inclined Plane.
9. WEDGE
A wedge is a triangular shaped tool, and is a portable inclined
plane, and one of the six classical simple machines. 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.[1][2] 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.
11. PULLEY
A pulley is a wheel on an axle or shaft that is designed to support
movement and change of direction of a taut cable, supporting shell is
referred to as a "block."
A pulley may also be called a sheave or drum and may have
a groove or grooves between two flanges around its circumference.
The drive element of a pulley system can be a rope, cable, belt,
or chain that runs over the pulley inside the groove or grooves.
Hero of Alexandria identified the pulley as one of six simple
machines used to lift weights.[1] Pulleys are assembled to form
a block and tackle in order to provide mechanical advantage to apply
large forces. Pulleys are also assembled as part of belt and chain
drives in order to transmit power from one rotating shaft to
another.[2][3]
13. WHEEL & AXLE
The wheel and axle is one of six simple machines identified by Renaissance
scientists drawing from Greek texts on technology.[1] The wheel and axle
consists of a wheel attached to a smaller axle so that these two parts rotate
together in which a force is transferred from one to the other.
A hinge or bearing supports the axle, allowing rotation. It can amplify force; a
small force applied to the periphery of the large wheel can move a larger load
attached to the axle.
Greek philosophers such as Hero of Alexandria first identified the wheel and
axle as one of the simple machines used to lift weights.[2] This is thought to have
been in the form of the windlass which consists of a crank or pulley connected
to a cylindrical barrel that provides mechanical advantage to wind up a rope and
lift a load such as a bucket from the well.[3]
The wheel and axle can be viewed as a version of the lever, with a drive force
applied tangentially to the perimeter of the wheel and a load force applied to the
axle, respectively, that are balanced around the hinge which is the fulcrum.
The mechanical advantage of the wheel and axle is the ratio of the distances
from the fulcrum to the applied loads, or what is the same thing the ratio of the
diameter of the wheel and axle.[4] A major application is in wheeled vehicles, in
which the wheel and axle are used to reduce friction of the moving vehicle with
the ground. Other examples of devices which use the wheel and axle
are capstans, belt drives and gears.
15. SCREW
A screw is a type of fastener, sometimes
similar to a bolt (see Differentiation
between bolt and screw below), typically
made of metal, and characterized by
a helical ridge, known as a male
thread (external thread) or just thread.
