Vector Diagram – Parallelogram Method for 4 different kinds of questions

For Combined Science Physics Olevel, when constructing vector diagram, a method called Parallelogram Method is commonly used.

Parallelogram Method is used when 2 forces are known, and the resultant (net) force R, can be found.

Below show 5 different variations of questions when can be solved by using Parallelogram Method:

(A) Body has acceleration, forces are unbalanced, there is a resultant force R (Newton’s 2nd law)

(B) Body at rest, all forces are balanced, there is no resultant force R (Newton’s 1st law)(C) Body moving at constant velocity, all forces are balanced, there is no resultant force (Newton’s 1st law)

(D) Finding unknown force (with resultant force R  + another known force are given)(E) Vector diagram is applicable to all vector quantities (with magnitude and direction). Not just for forces.