Question

CuesLIOLINOO
A cube of wood supporting a 400 g just floats on water. When the mass is removed, the cube rises by 2 cm. What is the side of the cube nea
(A) 1 : 414cm
(B) 14 : 14cm
(C) 24 : 24cm
(D) 28 : 28cm​

Answer 1

Explanation:

Let l be the side and ρ be the density of the cube.

Now, in initial condition

Weight of the cube + weight of mass placed above (200 gm) = weight of the water displaced

  l3ρwoodg+200g=l3ρwg

 l3ρwood=l3ρw−200....(I)

When the mass is removed

Then,

l3ρwoodg=l2(l−2)g....(II)

Weight of the block = up thrust

Now, from equation (I) and (II)

l3ρw−200=l2(l−2)

We know that, 

ρw=1

So,

  l3−200=l3−2l2

 l2=100

 l=10cm

Hence the sides of the cube is of 10 cm.