A worker moves a 30 kg box by pulling on it with a rope that makes a 60 degree angle with the horizontal. If the worker applies a force of 40 N and pulls the box over a distance of 20 m, how much work did the worker do

Ithink the answer is d

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.