Comic-book superheroes are sometimes able to punch holes through steel walls. (a) if the ultimate shear strength of steel is taken to be 2.50 x 108 pa, what force is required to punch through a steel plate 2.00 cm thick? assume the superhero’s fist has cross-sectional area of 1.00 x 102 cm2 and is approximately circular. (b) qualitatively, what would happen to the superhero on delivery of the punch? what physical law applies?

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.