What is resultant force | Different law of forces | Formulas

-

Definition of resultant force:


The resultant force is a single force that produces the same effect as produced by all the given force acting on the body. A resultant force also called the net force. The resultant force may be determined by the laws which are following below. 
  • Parallelogram law of forces
  • Triangle law of forces 
  • Polygon law of forces 

Parallelogram law of forces:


The law states that, if two forces acting simultaneously on a particle can be represented in magnitude and direction by two adjacent sides of a parallelogram. Their resultant maybe represent in magnitude and direction by the diagonal of a parallelogram which passes through their point of intersection. 

Parallelogram law of forces

Parallelogram law of forces


Now, let us consider two forces A and B acting at angle p. The resultant is given by the following formula. 
R = √ A2 + B2 + 2ABCosp 

If the resultant force R makes an angle q with the force B, then 
tan q = A sin p / B + A cos p  

Triangle law of forces:


The law states that, if two forces acting simultaneously on a particle, can be represented in magnitude and direction by two sides of a triangle taken in order. Their resultant may be represented by the third side of the triangle taken in the opposite order in magnitude and direction.

Polygon law of forces:


The law states that if a number of forces acting simultaneously on a particle can be represented by the sides of a polygon taken in order, in magnitude and direction. Their resultant may be represented by the closing side of the polygon taken in the opposite order, in magnitude and direction.

Some important notes:

  • The resultant of more than two intersecting forces may be found out by resolving all the horizontal and vertical forces. 
R = √ (∑H)2 + (∑V)2 
  • A number of forces acting on a particle will be in equilibrium when ∑H = 0 and.∑V = 0.
  • If the resultant of a number of forces, acting on a particle is zero then the particle will be considered in an equilibrium state. Such a set of forces, the resulting of which is zero, is known as equilibrium forces. 

Comments

Post a Comment

Popular posts from this blog

Difference between characteristic and universal gas constant

-
Some important point on the difference between characteristics gas constant and universal gas constant are explained below. Let us check out one by one below. You can also check out characteristics equation of gas , and general gas equation to know more about it. Difference between characteristics gas constant and universal gas constant: Constant gas characteristics vary from gas to gas but the constant of universal gas is fixed. If you working at human scales, then use universal gas constant, whereas if you want to gas constant that defined per unit mass of a specific gas, then use the specific gas constant.  The characteristic gas constant in equation P = RT is the value of R for a given gas for use. It is equal to the constant of universal gas divided by the molar mass of the particular gas. Characteristics gas Constant applicable for an ideal gas, whereas universal gas constant applicable for a real gas.  Units: Characteristics gas constant - k J / kg K and Univers
Read more

Varignon's principle of moments | Varignon's Theorem

-
Image
Varignon's theorem also called the principle of moments.  Varignon's Principle: Varignon's principle states that if a number of concurrent forces acting on a particle are in equilibrium, then the algebraic sum the moments that each force creates about a single point will be equal to the moment of their resultant force about the same point.   Varignon's Theorem From the above figure, F1 and F2 are two concurrent forces and their resultant is R. The moment produced by R with respect to a moment center O is R × d. The moment produced by the force F1 and F2 is respectively F1 × d1 and F2 × d2.  As per varignon's therorem R d = F1 d1 + F2 d2 Notes: This theorem initially stated for two concurrent forces, but, it is true for any system of forces and any number of concurrent or coplanar forces.  One of the practical applications of this theorem is to find the unknown reactions when a system is known to be in equilibrium under the acti
Read more

Difference between moment and couple

-
Moment and couple are two important concepts found in mechanics. They both terms describe the effect and cause of rotation in the system of forces , particle systems, and rigid bodies too.  What is a moment of a force? The turning effect produced by a force applied to a rotational system or on the body at a distance from the axis of rotation is called the moment of force . The moment of a force is the product of the force and the perpendicular distance of the point, about which the moment is required and the line of action of the force. What is a couple OR moment of a couple?   In mechanics, a couple refers to two equal and opposite forces, whose line of action is different from a couple . The couple also called a force couple or pure moment.  Points of difference between moment and couple are discussed below. So let us check out some key differences between them to know more about it.  Difference between moment and couple: The moment is the
Read more