A raft of wood (density`=600kg//m^(3))` of mass `120 kg` floats in water. How much weight can be put on the raft to make it just sink?

Options

A. 120 kg
B. 200 kg
C. 40 kg
D. 80 kg

Answer

D

Explanation

Volume of raft `V = ("mass")/("density")`
`rArr V = 120/600 = 1/5 m^3`
When the raft Is totally Immersed In water, It displaces `1/5m^3` water, so the 5 upthrus `= 1/5 xx 1000 xx g` newton
If x kg is the extra weight put on the raft to fully immerse it in water, then `(x + 120) g = 1/5 xx 1000 xx g`
`rArr x + 120 = 200 :. x = 80 kg `