| Work smarter, not harder. |
| Work smarter, not harder. |
A force is a push or a pull. Objects cannot move unless force is
applied to them. Force is also needed to make an object slow down,
speed up or change direction.
Friction is the force that slows down or stops an object.
In science, work is something that is done whenever a force moves
an object through a distance. Unless an object moves, no work is
done.
Simple machines are those powered by people. There are six types of simple machines: levers, inclined plane, wedge, wheel and axle, pulley and screw.
The lever is used to push, pull or lift things. A lever is made up of three parts: the fulcrum, the lever and the load. The force required to make it work is provided by a person. The fulcrum is the point of support, the lever moves the object which is commonly called the load.
An inclined plane is a flat surface on a slant. Ramps are inclined planes. Inclined planes reduce the amount of work required to move a load because the load is moved up a gradual slope instead of a short, steep, slope.
A wheel and axle is a simple machine that helps us to work faster without increasing our effort. There are two common types of wheel and axle: the first is where a wheel turns an axle, as in a doorknob set. Another machine of this type is the tricycle where pedals attached to the axle turn the wheel. The second common type of wheel and axle is the gear. A gear is a wheel and axle with teeth, the teeth of one gear mesh with the teeth of another and turn by the force of friction. Some gears have no teeth and are turned by belts.
Pulleys are wheels with raised sides to hold a rope or
a chain. There are two types of pulleys, fixed and moveable.
The fixed pulley does not decrease the amount of force necessary to raise
an object. It changes the direction of force so that the force of
gravity is added to help lift the load. Moveable pulleys move with
the object being lifted. Sailboat sails are lifted by both fixed
and moveable
pulleys. Moveable pulleys reduce the amount of force needed to
raise a load, usually by half.