In the figure below, the weights of the top, middle, and bottom blocks are are follows: • top block (WA) = 10 N • middle block (WB) = 50 N %3D • bottom block (Wc) = 30 N What is the maximum possible frictional force between the top block (A) and middle block (B)? H;=0.2 WA WB FA Hs=0.6 Wo Hs=0.3 O 2 N O 3 N O 30 N

The shaft AB is formed by bonding steel tube and a brass core. Outer diameter of the steel tube is 60 mm and the diameter of the brass core is 30 mm. The shaft is subjected to uniform distributed torque o t kNm/m. The allowable shear stresses for steel and brass are (Tsteel)all = 80 MPa and (Tbrass)all = 50 MPa, respectively. Determine a) the maximum value of the uniform torque t , b) the corresponding angle of twist at A. (The shear modulus for steel and brass are Gsteel = 77 GPa and Gbrass = 40 GPa, respectively) - Steel Tube A t kNm/m B 30 mm 15 mm 1 m 1 m Brass Core Cross Section