A 6.5-m ladder AB leans against a wall as shown. Assuming that the coefficient of static friction µg is the same at A and B, de the smallest value of µ, for which equilibrium is maintained. В 6 m A 2.5 m O 0.250 O 0.225 O 0.200 O 0.235 O 0.220

3 8. A flat plate ( 1.5 m ) long and ( 1.5 m ) wide is towed in water ( p = 1000 kg/m and v=1.31 * 10 * m? /s) in the direction of its length at a speed of ( 20 cm /s ). Determine; a) The skin frictional drag force on both sides of the plate. b) The boundary layer thickness at the end of the plate.

1. The two homogeneous bars AB and BC are connected with a pin at B and placed between rough vertical walls. If the coefficient of static friction between each bar and the wall is 0.4, determine the largest angle 0 for which the assembly will remain at rest. 20 in. 6 lb 8 lb 20 in.

The 12 kN crate is being pulled by the force P as shown in the figure. The force P makes an angle of e with the horizontal. a) Find the smallest possible force P to cause the crate to slide. b) Determine the angle e. c) Determine the horizontal frictional force acting at the bottom of the crate, W=12KN Note : The total surface R I Pmin - M= 0.20