A rectangular block of material is subjected to a tensile stress of 110 N/mm2 on one plane and a tensile stress of 47N/mm2 on the plane at the right angles to the former. Each of the above

stresses is accompanied by a shear stress of 63 N/mm2 and that associated with the former

tensile stress tends to rotate the block anticlockwise. Find:

(i) The direction and magnitude of each of the principal stress and (5marks)

(ii) Magnitude of the greatest shear stress.

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.