11. A vertical steel beam in a building supports a load of4.0 times 10^4 N. (a) if the length of the beam is 3.0 m and its cross sectional area is4.0 times 10^-3 m^2 , find the distance the beam is compressed along its length. (b) What maximum load in Newtons could the steel beam support before failing?
12. A defensive lineman of mass M = 115 kg makes a flying tackle at vi \= 4.00 m/s on a stationary quarterback of mass m = 76 kg, and the linemans helmet makes solid contact with the quarterbacks femur. (a) What is the speed vf of the two athletes immediately after contact? (b) If the collision last for 0.050 s, estimate the average force exerted on the quarterbacks femur. (c) If the cross-sectional area of the quarterbacks femur is4.0 times 10^-3 m^2 , calculate the shear stress exerted on the bone in the collision.