Question

A force F=k(yi+xj) where k is a positive constant acts on a particle moving in x-y plane 'starting' from the point (3,5), the particle is taken along a straight line to (5,7). The work done by the force is : ?

Answer 1

W = f vector dot d vector = k(yi+xj). dr=k (yi+ xj). d (xi+yj) = d(xy) = xy
Now putting limits
W = k(5*7-3*5)=(35-15)k=20kj