These are a type of simple machine.
LEVERS
A lever is a rigid bar tha can pivot ona point of support called fulcrum. It is used to lift load by applying force to a point on the bar. We call the applied force effort, whereas the load to be lifted or the resistance that must be overcome is known as the resistance.
The law of the lever, which describes the force of a lever in equilibrium, states that:
The result of the applied efford multiplied by the distance from the fulcrum must be equal to the result of the resistance to overcome multiplied by the resistance from the fulcrum.
CLASS 1 LEVERS
The fulcrum is located between the weight or resistance to overcome and the point where the force is applied.
CLASS 2 LEVERS
the fulcrum is at one end of the lever and the efford is at the other end. The resistance to overcome is located between the fulcrum and the effort
CLASS 3 LEVERS
The effort is located between the fulcrum and the resistance.
PULLEYS
Pulleys are used to lift heavy loads. They are wheels witha grooved rim.
FIXED PULLEYS
The axis of rotation of the pulley is fixes by attaching it to a support that prevents it from moving.
With fixed pulleys, we still have to put in the same effort to lift the weight, but they make the task easier by changing the dirction of the effort: when we lift weight without a pulley, we have lift them up, whereas when we use a pulley, we make a downwards effort, which is easier.
MOVEABLE PULLEYS
Moveable move vertically as well as turning when we pull on the rope. These pulleys reduce the efort required to lift a load by half.
Systems made up of moveable and fixed pulleys are called hoists. The force needed to lift a loadin a hoist is reduced in proportion to the number of moveable pulleys in the system.
Tecnology Ale and Cris 