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

Answer

C

Explanation

`v^(2) = u^(2) + 2aS`
`rArr 0 = (sqrt(2gh))^(2) + (2g-a)d`
by solving `a = (1+(h)/(d))g`
So the resistance offered by the wood