4-52 If there were 77500 grains/m2 in a pho- tograph of a metal taken at 100× mag- nification, calculate the ASTM grain size number (n).

5-78. The hatch door has a weight of 80 lb and center of gravity at G. If the force F applied to the handle at C has coordinate direction angles of a = 60°, ß = 45°, and y = 60°, determine the magnitude of F needed to hold the door slightly open as shown. If the hinge at A becomes loose from its attachment and is ineffective, what are the x, y, z components of reaction at hinge B? 2 4 ft 3 ft. 2 ft 3 ft C B X F Probs. 5-77/78

4-32. Determine the force P of Fig. P4-32 that will maintain equilibrium. 400lb P4-32

6-76 The triangular plate of uniform thickness shown in Fig. the two cables supporting the plate and the reaction at the ball support. has a mass of 400 kg. Determine the tensions in 900 mm B 1500 mm y

R5-5. Determine the x, y, z components of reaction at the fixed wall A. The 150-N force is parallel to the z axis and the 200-N force is parallel to the y axis. x Z 2 m 150 N 1 m 2 m 2.5 m -200 N