Question

how two farces are added up if they are not concurrent but in same direction ?

Answer 1

If two forces have somenon-zero angle between them, we can use a rule of parallelogram to add them as vectors. Forces are vector quantities, so their sum will also be a vector with a different direction. Normally, if forces are "in the same direction", that is the angle between them is less than 180 degrees, the resulting sum will be directed in between their directions. The magnitude of the resulting force can be calculated from the cosine theorem.