Force,Pressure,Stress & Strain

Force:-

• Definition:- force acts on free moving object which cause to acclerate or deccelerat. If the force acts on stationary object it can deform or eve break. According to Newton's Second Law: F= m X a . whereas ;
  
  
  

1. F: force in newton (N)



2. m: mass in kilogram (kg)



3. a: acceleration (m/s²)



4. 

Pressure:-

• Definition: Is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.

Whereas :-

1. P: pressure in Pascal (Pa)



2. F: force in Newton (N)



3. A: area in m²

Stress:-

• Definition: force acts upon an object which can not be moved.
  
  

where ,

1. Stress: N/m².



2. Force: N



3. Area: m²
   

Strain:-

• Definition: It is relative longitudinal change in body length.
  

There is no unit for strain.

1. L: original lenght.



2. ∆L: change in lenght.

The strain can be positive (tensile) or negitive (compressive).

Stress Vs. Strain:-

Hook's law describes the relation between the stress and strain as follows:

where,

1. σ: stress in N/m².
   
2. E: modulus of electricity of object in N/m².
   
3. ε: strain.

Measurment of force and pressure:-

Force: The simplest type of measuring devices is the spring balance. The scale is calibrated in Newton and/or gram.

Pressure: Mechanical measuring devices were designed where Bourdon tubes or bellows are used to produce a mechanical displacement that is transferrd to an indicating pointer.