Simple machines

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all machines have in common:

- involve a kind of motion.

- involve a kind of force.

- make a job easier to do.

- need some kind of input to make them work.

- produce some kind of output.

basic kinds of motion

- rotary: going round and round

- oscillating: swinging backwards and forwards.

- linear: in a straight line

- reciprocating: backwards and forwards in a straight line.

A machine is a device that helps make work easier to perform.

MECHANICAL ADVANTAGE: when a machine takes a small input force and increases the magnitude of the output force, a mechanical advantage has been produced.

CONSERVATION OF ENERGY: no machine can produce more work than the amount of work that is put into the machine.

THREE(SIX) SIMPLE MACHINES: lever, wheel and axle, pulley, inclined plane, wedge and screw.

WHEEL AND AXLE: a simple machine consisting of a large wheel rigidly secured to a smaller wheel or shaft, called axle.

PULLEY: a grooved wheel that turns freely in a frame called a block. used to: simply change the direction of a force or to gain a mechanical advantage, depending on how the pulley changes the direction of a force.

a) lever are classified into first, second and third class. they are simple machines because all of them let us balance a given resistance by applying a smaller force. FALSE. third class levers are always disadvantages.

b) a fixed pulley is a system that always let you lift a certain mass, with a smaller force. FALSE. A fixed pulley is a system that changes the direction of a force.

c) an axe could be thought as a sort of screw mechanism. FALSE. Tacha screw y pon wedge.

d) if you want tomove the earth by applying a small force, you should locate a fulcrum the closer to where you apply the force as possible. FALSE.  Cambia the closer to por far away from.

e) in the wheel and axle system shown below, the shorter BF is the handle, the easier it will be to lift the bucket. FALSE.  

a) PULLEY: a rope, a wheel with a   ______ in it and a weight make up this simple machine.

b) lever: this simple machine can be used to lift a weight. It has a fulcrum, or pivot point.

c) wedge: this simple machine can be used  to cut a part.

d) SCREW: it is made up of an inclined plane  circular ramp a cylinder.