Question

Comic-book superheroes are sometimes able to punch holes through steel walls.
(a) If the ultimate shear strength of steel is taken to be 3.00 109 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 1.10 102 cm2 and is approximately circular.



(b) Qualitatively, what would happen to the superhero on delivery of the punch? What physical law applies?

Answer 1

given thatshear strength p = 3 x 10⁹ paarea of cross section A = 1.10 x 10² cm²= 110 x 10^-4 m²a) force required to punch the steel plate F = PA= 3 x 10⁹ pa (110 x 10^-4 m²)=330 x 10⁵ N

b) on the delivery of the punch his first experiences a force which is equal in magnitude and opposite to the direction of the forceapplied by superhero this is according to newton third law of motion.

Answer 2

given that

shear strength p = 3 x 10⁹ pa

area of cross section A = 1.10 x 10² cm²

                                       = 110 x 10^-4 m²

   a) force required to punch the steel plate F = PA

                                                                           = 3 x 10⁹ pa (110 x 10^-4 m²)

                                                                           =330 x 10⁵ N

  

b) on the delivery of the punch his first experiences a force which is equal in magnitude and opposite to the direction of the force applied by superhero this is according to newton third law of motion.