A brittle material is mechanically tested in medium P in which it has surface energy γs = 0.9 J m^-2. This material has a fracture strength of 300 MPa for a given flaw size. The same solid containing the same flaws is then tested in medium Q in which γs = 0.1 J m^-2. The fracture strength (in MPa) in medium Q based on Griffith's theory is

Fatigue life is expected to increase by

A. increasing the size of the sample

B. smooth polishing of the surface of the sample

C. having compressive residual stresses at the surface

D. having tensile residual stresses at the surface

Which of the following is a function of a developer

A. Providing a contrasting background for visible dye indications

B. Making the penetrant water washable

C. Penetrating into discontinuities open to the surface

D. Dissolve organic soils on the test piece surface

With an increase in temperature, hardness of material . . . . . . . . and ductility . . . . . . . .

A. Increases, increases

B. Increases, decreases

C. Decreases, increases

D. Decreases, decreases

A brale indentor used in Rockwell hardness test has the following geometry and material.

A. Square based diamond pyramid with 136° included angle

B. Conical shape steel with 120° apex angle

C. Conical shaped diamond with 120° apex angle

D. 10 mm diameter hardened steel ball