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?

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shear stress is the measure of the material's resistance to cause "sliding" motion of its layers. 
Since the hero has to take a cylindrical piece of metal out, the area which will cause this force is 2*pi*r*l (put r and l in SI units to get answer in Newtons) 
so the force required is shear strength into this area (2.60109 * 2 * pi * r * l) 

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.