A wooden block is dropped from the top of a cliff 100m high and simultaneously a bullet of mass 10 g is fired from the foot of the cliff upwards with a velocity of `100 m//s`. The bullet and wooden block will meet each other after a time:

Options

A. 10 s
B. 0.5 s
C. 1 s
D. 7 s

Answer

C

Explanation

Let the bullet and wooden block meet at time t and at a height x above the foot of the cliff
Using, `h = "ut" +1/2 "gt"^2`
For the block, `(100 -x) =1/2 "gt"^(2) ( :.u=0 ) " "...(i)`
For the bullet , `x = 100t -1/2 "gt"^(2) " "...(ii)`
Adding equations (i) and (ii) , we get
`100 = 100 t " or " t = 1 s`