1. The problem statement, all variables and given/known data (see attachment) 2. Relevant equations 3. The attempt at a solution If a force a F acts on the farther end of the wrench, the torque due to it Fl where l is the length of wrench. The work done by this torque for one full turn is Fl*(2##\pi##) For wrench A, l=10 cm, and for wrench B, l=20cm. Therefore the ratio of work done is 0.5. But this is wrong. I don't understand why they have given the radius of the nut. I haven't used this information and I have no idea about where to use this. Any help is appreciated. Thanks!