Hammer of mass M strikes a nail of mass 'm' with a velocity 20 m/s into a fixed wall. The nail penetrates into the wall to a depth of 1 cm. The average resistance of the wall to the penetration of the nail is

Options

A. `(frac(M^2)(M + m)) xx 10^3`
B. `frac(2M^2)(M + m) xx 10^4)`
C. `frac( M + m)(M^2) xx 10^2`
D. `frac(M^2)(M + m) xx 10^2`