The tensile strength of brittle materials may be determined using a variation of equation 8.1. compute the critical crack tip radius for an al2o3 specimen that experiences tensile fracture at an applied stress of 275 mpa (40,000 psi). assume a critical surface crack length of 2 × 10−3 mm and a theoretical fracture strength of e/10, where e is the modulus of elasticity.

Aflywheel accelerates for 5 seconds at 2 rad/s2 from a speed of 20 rpm. determine the total number of revolutions of the flywheel during the period of its acceleration. a.5.65 b.8.43 c. 723 d.6.86

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.

For a gate width of 2 m into the paper, determine the force required to hold the gate abc at its location.