Question

The cover of a jar has a diameter of 8 cm. Two equal, but
oppositely directed, forces of 20 N act parallel to the rim of the
lid to turn it. What is the magnitude of the applied torque?

Answer 1

torque = force *r 
here 2 equal and opp foeces are acting 
therefore net force = 0
hence trrque is also = 0

Answer 2

The net forc will be 0 as 20N-20N=0 so the answer will be 0...