7. A body is subjected to a tensile stress of 1200 MPa on one plane and another tensile stress of 600 MPa on a plane at right angles to the former. It is also subjected to a shear stress of 400 MPa on the same planes. The maximum normal stress will be
9. A thick cylindrical shell having ro and ri as outer and inner radii, is subjected to an internal pressure (p). The maximum tangential stress at the inner surface of the shell is
10. A composite shaft consisting of two stepped portions having spring constants k1 and k2 is held between two rigid supports at the ends. Its equivalent spring constant is