[填空题]
A person exerts a force of 55 N on th ur ib)1f9-rayejatogvp)myrh /4+2.e end of a door 74 cm wide. What is the ::t h/7 nwv wb6ygmjvjjz;;.1 2lpybomagnitude of the torquygo:j y tv62h nz7wb:j1p;l;v/ .bm jwe if the force is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$