An open knife of mass m is dropped from a height h on a wooden floor. If the blade penetrates up to the depth d into the wood. The average resistance offered by the wood to the knife edge is .

Options

A. `mg(1+(h)/(d))`
B. `mg(1+(h)/(d))^(2)`
C. `mg(1-(h)/(d))`
D. `mg(1+(d)/(h))`

Answer

A

Explanation

(a) Work done by resistive force =Change is PE
`rArr " " F.d=mg(h+d) rArr F=mg(1+(h)/(d))`