[填空题]
The bolts on the cylinder hea 7f.+uwm*e1jjg wmm,qd of an engine req2uvhrqyu7 b iyd.l;* u(tgli/yp v//9uire tightening to a torque of 38 (d;7y /pul l i.v/b/2iu rtgqyu9yh *v$m \cdot N$ 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