A pulley is a wheel with a groove that holds a rope or cable and changes the direction of a pulling force. Pulleys are often used in sets to reduce the amount of force needed to lift a load, though the total work required remains the same. Pulleys have many applications, including lifting objects with cranes and in automobiles and airplanes. A wedge is a piece of material thick at one edge and tapered to a thin edge, used for splitting, tightening, or levering. Examples include knife blades and scissors. An inclined plane is a surface set at an angle to the horizontal that raises or lowers loads by rolling or sliding, such as a ramp.
2. PULLEY
A pulley is a wheel with a groove along its edge for
holding a rope or cable. It is a simple machine that helps change
the direction and point of application of a pulling force. Pulleys
are usually used in sets designed to reduce the amount of force
needed to lift a load. The magnitude of the force is reduced, but it
must act through a longer distance. Consequently, the amount of
work necessary for the load to reach a particular height is the
same as the amount of work needed without the pulleys.
Pulleys can be found in many different applications
around us. Not only are they used for the obvious lifting of objects,
such as by cranes, but they are also used in modern automobiles
and airplanes. Pulleys are also essential for most machines in
some form or other.
4. WEDGE
A piece of material, such as metal or wood, thick
at one edge and tapered to a thin edge at the other for
insertion in a narrow crevice, used for splitting, tightening,
securing, or levering.
