Applied mechanics

INTRODUCTION:-

   @ Applied mechanics :-

               the branch of science which deals with the focus and their effects on the bodies on which they act

# Branches of applied mechanism :-

  i) Static :-
           the  branch of applied mechanism which deals with the force and their effects whie acting upon bodies which are at rest        
ii) Dynamic ( further divided into Kinetics and Kinematics ) :-
                        the branch of applied mechanics which deals with the forces and then effects while acting upon bodies which are at motion
* Kinetics :-
       the branch of dynamic which deals with the relationship between  motion of bodies and forces causing motion
* Kinematics :-
             the branch of dynamic which deals with the motion of bodies without considering the forces causing motion

# rigid body :-

     a roigid body may be defined as a body which does not change in shape and size under the effects of forces acting over it, in other words, a rigid body is one whose particles remain at the same distance from each other how ever heavy forces may act on it. nobody is perfectly rigid

@ Some important defination :-

          - Body :-
              a smallest matter or portion of matter occupy space while considering is known as body
- deformable body :-
       The body is said to be deformable body which changes its size or shape under the action
- density :-
       * it is the ratio of mass to the volume , also written as m/v , where m= mass and v= volume
    * it is vector quantity
    - Distance :-
        the length of path covered between initial and final portion
- Displacement :-
         the shorter distance covered between initial and final position of a body
- speed :-
         distance covered per unit , it is scaler quantity
- Velocity :-
         distance covered per unit time in a particular direction , it is denoted by v. it is vector quntity , its unit are m/sec
- acceleration :-
      the rate of change of velocity is known as acceleration . it is denoted by small a.
- force :-
      it is a pull  or push which changes or tends to change the state of rest or motion of a body
- mass :-
   * the quantity of matter in a body is called mass
   * it is scalar quanlity
   * It is constant thropughout
   * It cannot be zero
    * its SI unit is kg
- weight :-
         it is the force by which a body being attracdted towards the centre of earth . the force may vary from place to place and it will be zero at the centre earth

    Note :-

       the velocity of sound in air is aboout 340 m/sec

=> detection of submerged object :-

          ultrasonics get reflected solid objects, therefore the presence of submerged objects in the sea like ice berg, glacier, submerine can be detected from  a large distance and the captain of the ship can change the direction

   => cold welding :-

                  when the properties such as brightness, brittleness etc of some metal sheets change on heating . they cannot be welded by electric or gas welding in such cases the sheets are joined together by using ultrasonics to do this sheets to be welded are put together below the tip of the hammer. the hammer is attached to the rod is placed in the coil and the rod begins to more up and down very rapidly and the molecules of the metasl sheets  starts vibrating and diffuse into molecules of each other, therefore , the two sheets get welded without heating