Question

When or when not are we supposed to use the vector form of a formula as for example, EX: W=F(vector) X R(vector) =F.R sin∅ this can also be written as, W=F.R How are we supposed to know if we are supposed to use which formula?

Answer 1

Explanation:

it depends on the theory actually.

But as a quick rule to remember, if your LHS is a vector, then you use the cross product, i.e. FxR

because cross product of 2 vectors gives a vector. Ex. Torque T = FxR, here all 3 quantities are vectors.

but if your LHS is a scalar, then use a dot product, F.R because dot product gives a scalar.

Ex. Work W = F.S here Force F and displacement S are vectors, but work W is a scalar.

hope it helps. please follow.