Force And Pressure ( Class 8 ) Notes

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 Force And Pressure

# Force : 

         -The external agent which can changes the speed and the direction of motion on the shape of body.

         - force is  a push or pull which can change or try to change the state of motion of the body.

  • It is represented by F.
  • Unit of force is Newton (N)
  • It is a vector quantity. 
                                        F = M.A   
                   


 # Types of force :-

  1. Fundamental force :

            a) Gravitational force
            b) electromagnetic force
            c) weak nuclear force
            d) strong nuclear force

  • Among of these four forces gravitational force is weakest and strong nuclear force is strongest.
  • Gravitational , nuclear forces are attractive in nature . but a electromagnetic force may be attractive or repulsive .
  • Gravitational and electromagnetic force are long range force but nuclear force are very short range force . 

  2. Derived force : 
               All persists except fundamental force are called as derived force .
       Example :- muscular force, frictional force, mechanical force .

   
 3. Contact force :  
              Force that arises with the contact up to armor objects involved are called as contact force.

 
 4. Non-Contact force :
              Force that arises without the contact of two or more objects involved are called as non-contact force.



  5. Balance force :
                 It is comparison of two or more . If the result of forces in a body is zero those force is are known as balance force.
  Ex. Tug a war




  6. Unbalance force :
                When two or more forces causes change in state of motion Then it is called unbalance force .
  ex. If you kick a football and it moves from one place to another.




# Pressure : 

               - pressure is defined as the physical force exerted on an object the force applied is perpendicular to surface of objects per unit area.

  • It is represented by capital 'P'
  • It is a scaler quantity.

# Types of Pressure :     

  1. Absolute
  2. Atmospheric
  3. Differential
  4. Gauge                                           

                                                                  P = F/A 

                                  




                                                     
                                            

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