SIMPLE MACHINE

The device consisting of very few parts that makes work easier, faster or more convenient is called simple machine.

  • Complex machine are formed by combination of many simple machines.

  • Functions of simple machines are :

  1. A simple machine is used to overcome a load by applying small force.

  2. A simple machine is used to change the direction of force.

  3. A simple machine increases the speed of work.

  • Effort is the force applied to the machine.

  • Load is the force applied by the machine to the body.

  • Fulcrum is the support point required to turn or rotate the machine.

  • The distance of effort from fulcrum is effort arm.

  • The distance from fulcrum to load is load arm.

  • The work done on the machine is called input work. Input work = effort × effort arm

  • The work done by the machine on the load is output work. Output work = Load × Load arm

  • The ratio of load overcome by a machine to effort applied in the machine is mechanical advantage.

  • Mechanical advantage =  loadeffort

  • The velocity ratio of a simple machine is the ratio of effort arm by load arm.

  • Velocity  ratio = effort armload arm

  • The ratio of output work to input work in a machine is efficiency of a machine.

  • Efficiency = output workinput work ×100%

  • Principle of simple machine states that in a perfect machine, work done by the machine is equal to the work done on the machine.

  • Work done by machine = work done on the machine

  • There are 6 types of machine. They are:

  1. Lever

  2. Pulley

  3. Wheel and axle

  4. Incline plane

  5. Screw

  6. Wedge

  1. Lever is a rigid bar capable of rotating about its fulcrum. There are 3 types of lever they are:

  1. First class lever

  2. Second class lever

  3. Third class lever 

  1. First class lever: fulcrum is between load and effort

  2. Second class lever: load is between load and effort

  3. Third class lever: effort is between load and effort

  • It is a simple wooden or metallic machine that uses a wheel and rope to lift heavy loads by multiplying the effort to load.

  • A wheel and axle is an arrangement of two co-axial cylinders of different radii attached to each other.

  • An inclined plane is a smooth rigid flat surface that makes an angle with the horizontal plane.

  • A jack screw is a simple machine used to lift heavy loads.

  • Wedge is a simple machine used to cut objects into pieces.

  • The turning effect of force is called moment. 

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