[填空题]
The bolts on the cylinder hea pd40pv 39wfcrv*z1- (zsuydd d of an engine require tightening to a torque of 38(*u-1 vsydzdz $m \cdot N$ If a wrench is 28 cm long, what force perpendicular to the wrench must the mechanic exert at its end? N If the six-sided bolt head is 15 mm in diameter, estimate the force applied near each of the six points by a socket wrench (Fig. 8–41). N