A bullet from a gun is fired on a rectangular wooden block with velocity u. When bullet travels 24 cm through the block along its length horizontally, velocity of bullet becomes u3. Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is :
- 24 cm
- 28 cm
- 30 cm
- 27 cm
Answer
(4) 27 cm
Solution
Let the uniform retardation be a.
First 24 cm: v2 = u2 - 2as
u29 = u2 - 2a(24)
48a = 8u29
a = u254
Total distance till rest: L = u22a
L = u22u2/54 = 27 cm
Answer: (4)