Question

If f is the forece acting on a particle having position vectorr andt the torque of the force

Answer 1

the cross product of r and F (i.e T)is perpendicular to both r and F....now the question is how come r.T and F.T= 0 ....this is how: the dot product of two vectors can be written as a.b cos theta(a and b being two vectors...) as cos of 90 degrees is =0 and since T is perpendicular (at 90 degrees)to both r and F ...the result comes out to be zerooo....... HOPE THAT HELPED :)