[填空题]
A person exerts a force of 55 N on thebn scn6r*q6-qv9a(ce end of a y4hbf.zce ;(hpx u+s7u nhi022xb;j udoor 74 cm wide. What is the magnitude of the torque if the fory z j h4;p(ixnhuehbc+uu7f s2x;02b.ce is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$