SIMPLE MECAHNISM

SIMPLE MECAHNISM :-

         simple machine may be define as a device which unable we to do some useful work at some point fame

@ Compound machine :-

            it may be define as device consisting of a number of simple machine which unable us to do some useful work at a faster spin or with much less effort

@ Effored :-

        the force applied on a machine to lift the load or to overcome the resistance is called effored , it is denoted by p

@ input of a machine :-

        Amount of work done on a machine is known as input, it is the product of effored and distance y  threw which it has moved in the direction of effored, input= p><y

@ Output of a machine :-

                it is a product of load 'w' lifted and work distance 'x' threw . which load is lifted , output = w >< x

@ Mechanical advantage :-

              the ratio of load lifted by a machine to the effored applied is called mechanical advantage
MA= load lifted/ efford apply= w/p, it value is always >1

@ Velocity ratio :-

         the ratio of distance moved by the effored to the distance moved by the load
VR= Distance moved by the effored/ distance moved by the load = y/x

@ Efficiency of a machine :-

                the ratio of output of a machine to the input of a machine . it is equal to output/ input= w >< x/ p><y ><100, it is generally express a % . it can be be greater than 100%

@ Ideal machine :-

         it is efficiency of a machine is 100% , the output of machine= input of machine is called ideal machine , MA=VR
relation between mechanical AVR and effeciency of a machine
let, W= load
P= efford
Y= distance moved by efford= y/x
X= distance moved by load
we know that mechanical advantage MA= W/P
VR= Y/X
V is also known as input of a machine = PY
output = WX

@ Reversible machine :-

            sometimes a machine is also capable doing some work in the reverse direction after the effored is removed such the effored are called reversible machine. water bake falls that in the wall on the removal

@ Condition for reversibility of machine :-

      its effeciency should be greater then 50%
input = P ><Y              output = W >< X
work last in friction = input- output
= P >< Y - W >< X
in a reversible machine is the output on a reversible should more than mechanical friction

@ Self locking machine / irreversible machine :-

 # Law of machine :-

          the team of machine may be defined as the relationship between effored applied and load lifted for actual machine , P= mW+ C
where m = slope
           c= Intercept
for machine P= mW+C
maximum mechanical advantage , we know that MA= W/P
= W/mW+C
= 1/ m+ C/W
MA= 1/ m+C/W
 smalled denomileter greater will be m. advantage , when the value of w is extremely high , the team C/W will be neglective . maximum MA= 1/m
- Maximum efficiency = MA/VR
we know that
= MA/ VR
= W >< X/ P >< Y
= W / P >< VR
= W/ mW+C >< VR
= 1/ mCVR
= max. MA/ VR
from these two article it can be calculated that
- Mechanical increases in load
- effeciency increases with load
- mechanical advantage will be max. at a high value of load

@ Worm and Worm wheel :-

         it consist as a straight rod with teeth cut on it known as worm and worm wheel, worm wheel is provided with a load drump concentric with it a row is bound on the load drum one and of the row is fixed to the drum wheel the other and carries the load, let,W is equal to load lifted P is equal to load lifted P is equal effored applied
L = length of lever
R = radius of load drum
T = Number of teeth on the wheel distance moved by the effored in one regulation of the handle is equal to 2><pie><L
    if the worm is single treated then for one regulation of the handle the load drum will mout through is = 1/t regulator
distance moved by the load 2>< pie><r/t
velocity ratio = Distance moved by effort / distance by load
= 2 >< Pie >< L/ 2 >< Pie >< r/t = LT/ Pie
=> MA= W/P
=> MA/ VR = W/P/ LT/Pie

@ Screw jack :-

       Screw jack :-
             it is a device which is used for lifting load by applying comprehensively smaller effort at the end of handle and efford P is applied in the horizontal direction to lift the load W
let L= length of the handle
p= Pitch of screw
W= Load
P = effort
we know that distance moved by the effort in one revolution , if the handle is 2 >< pie >< L
distance moved by load = p
VR= distance moved by effort / Distance moved by the load
which is = 2 >< pie ><L/ p
if the screw is double treated than for one revolution if the handle the load will be lifted threw 2p
VR= 2 ><pie ><L

@ Relational effored P and weight lifed by screw jack

-> Let p = pitch of the screw
d= diameter of the screw
alpha = helix angle
then tangent alpha = p/ Pie >< Alpha
horizontal force required to lift a load on a inclined plain
P= W tan ( alpha + theta)
where theta= angle of friction

@ Pulley :-

       it consist of two parts, the sheave at the block the sheave is a wheel of metal with groove cut in it ceremon furnace round with a row coin dass, it is mounted on an axel . which is fixed to a from called the block. the sheaved rotate in the block, the pulley is known as fixed pulley , if the block is fixed the pulley is movable pulley if the block is movable

# System of pulley :-

    i) First system of pulley :-

                 in this pulley are movabale , therea re separate wire for each pulley therefore this system of pulley one and of each stream is tied to the fixed spot while the other end passing round the periphery of the bottom pulley passing through the block of knot higher pulley

ii) Second system of pulley :-

         this system also known as pulley block system consist of two block one upon and the other  lower the upper block is fixed while the lower block is movable both block carry equal number of pulley , there is only one stream which passes round all pulley one end of the stream is fixed to the upper block while the other end of the stream is free and P is apply to this free and if there are n number of pulle in both the block end the load is to be lifted threw x then the effort is moved , there are distance y which is equal to nx, velocity ratio = nx/x= n

iii) Third system :-

             this is also known as separate stream attach to the wait system , in this system the pulley are arranged so that there as many stream as total number of pulley one end of the stream is fixed end of the stream passing round the upper portion of the pulley is attached to the next pulley