Question

At what angle do the force p+q and p-q acts so that the resultant is 3p^+q^.

Answer 1

Answer:

Force 1 = p + q

Force 2 = p - q

R^2 = A^2 + B^2 + 2ABcostheta

Resultant is given as 3p + q.

Hence,

(3p + q)^2 = (p+q)^2 + (p-q)^2 + 2(p+q)(p-q)costheta

Expand it and simplify you will get the answer as

2p^2 = 2(p^2 - q^2) costheta + p^2 + q^2

Simplify it more you will get

cos theta = 1/2

theta = 60 degrees.

Hence angle between the vectors is 60 degrees.