Why is sometimes component of some forces added in the same direction and some are equated to each other??? Can't understand the concept...please help!!

Dear Anurag

We have to always form a equation i.e. F=ma    If in case a=0 then forces are equated to get unknown forces and if two forces are in same direction then we need to add. If forces are in opposite direction then also we have to which looks like they are equated. e.g. If F1 and F2 are acting in opposite direction and acceleration is zero then F1+(-F2)=0 hence F1=F2.

All the best.

AKASH GOYAL

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Approved

by vector law of addition net force = (F₁²+ F₂²+2F₁F₂COS@)^1/2

when forces are in same direction along the same line then @ becomes 0 & net resultant R

R =F₁+F_{2 ........1}

when they act in opposite direction then @ becomes 180 & net resultant R

R =F₁-F_{2 ......2}

in this case if magnitude of both forces is same then resultant becomes zero...

eg)force is applied on a block but it dosent move due to friction ,here friction force & applied forces are in opposite direction & equal in magnitude....

Approved

Thank you vikas sir and akash sir....both of you helped me a lot in the concept, hope, to have such help throughout my preparation.