Important Question from Simple Machine

1)Why are winding roads made on the hills?
Winding rads are made on the hills because winding roads are the form of inclined plane having longer
distance and makes our work easier my magnifying force.


2)Why is the efficiency of a simple machine is
 always less than 100%?
When the output work is equal to the input work,but some part of the input work is lost in overcoming friction,the efficiency of a simple machine is always than 100%.


3)Why is it easier to apply force downward?
It is easier to apply force downwards because the force is applied influence the gravity.


4)Why is the blade of a metal cutter shorter than that of scissors used by tailors?
In metal cutter the effort distance is greater. Metals are very hard. In order to cut the metals we need more energy and effort.If the effort distance is greater than load distance there  will be magnification of force and the metals would easily could cut.So  the blade of a metal cutter shorter than that of scissors used by tailors.


5)How does a wedge work?
When we apply effort the sharp end passes inside the material and cut the things.In this way wedge works.


6)How does wheel and axle work?
Wheel and axle is a co-axial two cylinder .the ropes
are wound around the wheel and the axle.The ropes are wound in opposite direction.The effort is applied in the big cylinder and load is lifted by a small cylinder. When the rope is wound around the wheel is pulled downward,the load wounded around the axle is raised upward.


7)Why is the mechanical advantage(MA) more in movable pulley?
The mechanical advantage is more in a movable pulley because it moves up and down changing its position. Due to which ED is greater than LD which helps in magnification of applied effort. 


8)What is the method used to increase the mechanical advantage of a inclined plane?
There is only one method to increase the mechanical  advantage of a inclined plane that is increasing the length of slope which increases of mechanical advantage of an inclined plane.   




          

Inclined Plane

Inclined plane
Inclined Plane is a slope ramp which is used to lift the load a gradually by using less effort.It is a force multiplier.


The distance where the load should be taken is length of slope or distance travelled by effort. It is denoted by "l".

The length of height of slope is the distance travelled by load.


VR =         length of slope          
            length of height of slope
      =   l  
           h


                               "OR"



VR =       distance travelled by effort   
                distance travelled by load
       =   l  
            h

Wheel and axle

Wheel and axle
The type of simple machine which consist of two co-axial cylinders of different diameters which a mounted on the axle.
  
Diameter
A diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle.  


Radius 
Radius  is a line segment from the center to the perimeter (surrounding area) of a circle. Half of a diameter is the length of radius.


In wheel and axle radius is the effort distance.
Radius of wheel is denoted by capital r "R" where as radius of axle is denoted by small r "r".


# Generally effort is applied in a big cylinder and load is applied on a small cylinder which means ED  is greater than LD.
Mathematically,
VR = ED 
         LD
      =  Radius of wheel 
          Radius of axle
       =   R 
            r 
Therefore VR of wheel and axle is =   R 
                                                              r  
We know radius of wheel is greater than the radius of axle which makes the VR greater than 1 and more easy by magnification of force.

Types of Simple Machine

Types of Simple Machine
There are Six types of lever. They are:- 
1) Lever                                 4) Inclined Plane
2) Pulley                                5) Screw
3) Wheel and axle                  6) Wedge


Lever
Lever is a rigid bar which is capable to rotate a fixed point called fulcrum.


Rembemer:- If the effort distance is greater than load distance magnification of force is there and the work can be done easily 


Fulcrum is denoted as Δ , load as ¨ effort as $or# in the figure.
There are three types of lever. They are:-
1) First class lever
2) Second class lever
3) Third class lever 


First class lever
The lever in which fulcrum is between load and effort is called first class lever.
















In First class lever 
Ld < Ed
Ld > Ed
Ld = Ed
Ld ≠ Ed


Second class lever
The type of lever in which load is in between fulcrum and effort. 
















In Second class lever Ed is always greater than load distance which magnification of force and make our work easier.


Third class lever
The type of lever in which effort is between fulcrum and load.















In Third class lever Ld is always greater than Ed in which there is no magnification of force and makes our work more difficult. MA of Third class lever is less than 1.

Ratio defination and formula

Mechanical Advantage (MA)
Mechanical Advantage of a machine is defined as a ratio of a load overcome by the machine to the effort applied in the machine.
Mathematically,
                           MA=    load   
                                       effort 
            i.e            MA=    L   
                                        E

It has no unit as it is the ratio of  two force.

What is meant by a simple machine having MA3?
It meant that we can overcome the load of 3 Newton (N)  by applying the effort of 1N using simple machine. 


Velocity Ratio (VR)
Velocity Ratio is defined as a  ratio of effort distance to load distance.

Mathematically,
                            VR=    effort distance   
                                        load distance 
            i.e             VR=    ED   
                                         LD

Efficiency
It is the ratio of work output to work input per 100%.

Mathematically,
                 Efficiency=    Work output  
                                        Work Input 
                                 = L Í LD 
                                    E Í ED

         =  L  Í  LD 
                                     E       ED 
         =   L    ÷ ED 
                                         E       LD                             
                                                 =  MA ÷ VR 
                                 =   MA 
                                       VR
           i.e   Efficiency=   MA 
                                        VR