2. Throughout history, humans have developed a
number of devices to make work easier. The most
notable of these are known as the "six simple
machines": the wheel and axle, the lever, the
inclined plane, the pulley, the screw and the wedge
11. Class 1:
Fulcrum in the middle: the effort is applied on
one side of the fulcrum and the resistance on
the other side, for example, a seesaw,
a crowbar or a pair of scissors. Mechanical
advantage may be greater or less than 1.
12. Class 2:
Resistance in the middle: the effort is applied
on one side of the resistance and the fulcrum
is located on the other side, for example,
a wheelbarrow, a nutcracker, a bottle
opener or the brake pedal of a car. Mechanical
advantage is always greater than 1.
13. Class 3:
Effort in the middle: the resistance is on one
side of the effort and the fulcrum is located on
the other side, for example, a pair
of tweezers or the human mandible.
Mechanical advantage is always less than 1.
14. Wheel and Axle
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.
15. Importance of Simple Machine
Screws - used to hold different parts of machines
Pulley - make it easier to pull a rope, to change the
direction of a force, or to get more mechanical
advantage and lift something heavier than you can lift
Inclined plane - a load can be pulled up the plane by a
sideways input force and heavy objects may be lifted.
Wedge - can take something apart that is really big
and it is easier to move
Lever -helps you move something heavy, or make
something go fast.
Wheel and Axle – used to lift weights.
16. General Importance of Simple
transferring a force from one place to another,
changing the direction of a force,
increasing the magnitude of a force, or
increasing the distance or speed of a force.