In an orthogonal cutting operation on a work piece of width 2.5mm, the uncut chip thickness was 0.25 and the tool rake angle was 0(zero) degrees. It was observed that the chip thickness was 1.25mm. the cutting force was measured to be 900N and the thrust force was found to be 450N. find the mean shear strength of the work piece material and if the coefficient of friction between the chip and the tool was 0.5, what is the machining constant.