The mean diameter of a Whitworth bolt having V-threads is 25 mm. The pitch of the thread is 5 mm and the angle of V is 55. The bolt is tightened by screwing a nut whose mean radius of the bearing surface is 25 mm. If the coefficient of friction for nut and bolt is 0.1 and for nut and bearing surfaces 0.16 ; find the force required at the end of a spanner 0.5 m long when the load on the bolt is 10 kN.