Which of the following about hardness is true It reflects a

Which of the following about hardness is true? It reflects a material\'s resistance to local plastic deformation It is measured using the tensile testing A larger indent means higher hardness The yield strength of a material can be estimated from the hardness value A specimen of copper (elastic modulus 110 GPa) having a rectangular cross section 15.2 mm times 19.1 mm is pulled in tension with 44, 500 N force, producing only elastic deformation. Calculate the resulting strain. 1.39 0.139 0.0139 0.00139 A cylindrical specimen of a nickel alloy having an elastic modulus of 207 GPa and an original diameter of 10.2 mm experiences only elastic deformation when a tensile load of 8900 N is applied. Compute the original length of the specimen if the maximum allowable elongation is 0.25 mm. 475 mm 350 mm 35 mm00.58 mm

Solution

A.option a...resistent to indention

B.strain=p/aE=44500/(15.1*19.1*110*1000)=0.00139

C.e=pl/aE=475.1279