Laws of motion

Force:-As we know that capacity to do work is Force.But force changes and tends to change the state of rest or motion of a body.It is measured in newton(S.I. system) which is denoted by N.

1 Newton force = is amount of force required to accelerate one Kg of mass at a rate of 1 m/s²

^{Types of forces:-}

^{Representation and resolution of forces:-Force is a vector quantity and it is represented by arrow.}

^{x - component of force (x - axis)}

^{y - component of force (y - axis)}

^{Transmissibility of a force:-When a force acts upon a body,its effect as same if it is the same line of action.}

^{The force P will have same effect if it is acting on any point on the}^{line of action}^.

^{Free-body diagram:-The free diagram,which is an isolated view of the body,which shows only the external forces exerted on the body.}

^{Parallelogram law of forces:-If two forces acted on a body can be represented by sides of parallelogram,then their diagnol is represented as resultant of two forces.}

^{Let their are two forces P and Q,and resultant of two forces is R;angel between two forces is}Ѳ and angle between resultant and a force is α .

Cases of Parallelogram law:-

Force system:-It is a collection of forces acting on a body in one or more planes.

Co-planar force:-Forces whose vector lie in the same plane is called co-planar force.
Con-current force:-Forces whose vector lie from a same point.
Co-linear force:-Forces whose vector lie in same line of action.

Triangle law of forces:-If two forces are acting from a same point and represented from of triangle as its two sides then their resultant is represented by third side taken in opposite direction.

Let P and Q are co-planar con--current forces,the resultant R can be obtained with the help of triangle law of forces:-

Polygon law of forces:-If two or more than two forces that are co-planar,con-current acting from a point by sides of polygon,taken that resultant is represented by closing sides of polygon in opposite order.

This is the extension of triangle law of forces because you can see in fig-2 ob is resultant of oa and ab,oc is resultant of ob and bc and finally od is resultant oc and cd.

Resultant of forces:-