The state of stress at a point in a solid is given as 10 5 5 7 xy MPa. Consider a plane passing through this point with normal vector n = (1/ √ 2)ex + (1/ √ 2)ey. What are the normal and shear stresses on this plane?

An inventor claims to have developed a reversed heat engine (ie. a heat pump) which is able to deliver 10 kj heat into the room at 20°c from outside ambient temperature of -10°c by consuming only 2 kj electricity in winter. this claim is a)-impossible b)-possible only if the heat pump is ideal c)-practically possible d)-unable to be assessed as it depends on the working fluid used in the heat pump.