Simple Machine and Compound Machines

Simple Machine and Compound Machines

A simple machine is a device  that makes our work  easier and faster .Scissors, knives, tweezers and  tongs  are some example  of simple machine .

Simple machine are of different  types leavers , pulley , inclined plane ,screw, wheel and axle and  wedge.

 

Lever 

 You must have seen that we  can easily open the  the  tin cap of soft drink bottle  using a bottle - opener. similarly we can lift heavy objects  using a rod . The bottle opener  and  the rod  are examples of lever 

A simple machine  that turns around a fixed point is called  a lever .

a lever helps us to do more work by applying less force  . this makes our work easier . the Terms  related  to a lever  are - Load, effect and fulcrum.  

1. The  Object on  which work is  to be performed is called load (L)

2. The force applied on a lever to lift( or move) the load is called effect (E)

3. The fixed point on which a lever turns is called fulcrum( F) 

Classes of levers 

There  are mainly three classes  of levers depending on the potions of the load (L), effort (E) and fulcrum(F)

1.First class lever : in first class lever , fulcrum is in between the load and  effort. Some examples of this type of lever are  crowbar , See-saw , scissor, spoon, etc. 

2. Second -class lever : in Second class levers load is in between the  fulcrum and effort. some examples of second - class lever are wheel- barrow, nut cracker , Bottle cap- opener , etc

3. third -class lever : in third- class levers , the effort is in between the fulcrum and load. Some examples of third- class levers are  forces, ice  tongs, knife , staple  machine , etc

 Pulley 

it is difficult;t to lift  a bucket full of water  from a well but you can do this easily when you use pulley. A pulley consists of a particular disc made of metal or wood with a groove  cut along its  rim. A  rope passes around the  groove  prevents the rope from slipping off the disc. the pulley rotates about  an axle fixed to a support .Inclined Plane 

 A simple machine trhat has a sloping  surface is called an inclined  plane. some examples of inclined plane are ramps sloping wooden planks , Slides , etc . Inc;lined  planes are provided  in the hospitals so that wheel chairs carrying  patients can easily be pushed .

Screw 

A screw looks like a nail with groove cut into . it . It has a winding  edge called thread. To insert a screw  in a wood , it is screws in by turning  it round  and round  with screw - driver . Less force  is needed to insert  a screw  in the  wood  than the nail. The srew  can hold  things  together  tightly. A screw jack is an examples  of a screw   .

Wheel and Axle

Each time  you turn the knob of  your water tap or the door  knob of  your house, you are using a simple machine , that is , a wheel and axle. A wheel with a road attached to it is called a wheel and  axle arrangement .

When we  turn the wheel, the axle  also turns . in a  screw driver , trhe thick handle  works a  the wheel and the  thinner  metals rod as the axle. With this arrangement , it tkes less force  to move  something . other examples  of wheel and  axle are the steering  wheel of a car and  a drill used  by carpenters

Wedge

 It is a  V- shaped  piece, generally made of metal. It has two inclined planes  put together  to form a sharp  edge. a blade , an axe  and knife  are examples  of wedge. It is used to cut  and split things 

Compound Machine

When you open up a clock, you find several simple machines inside it . Similarly , the cars, aeroplanes, sieving  machines  also . consist of several simple machines.

Machine that consist of  several simple  machines s are called  complex  machine  or  com,pound  machines .

 Machines  have made our  life  simple . We  must take  care  of machines and maintain them property .