A hollow spherical body of inner and outer radii 6 cm, and 8 cm respectively floats half submerged in water. Find the density of the material of the sphere.

Answer

C

Explanation

`r_2=8cm, r_1=6cm`
`Here m_2=upward thrust
`rarr V_(pg)=(V/2)(rho_2)xxg`
`[where rho_w=density of water]`
`rarr(4/3pir_3^2-4/3pir_1^3)rho=(1/2)rP_2^3xx1`
`rarr (r_2^3-r_1^3)xxrho=(1/2)r_2^3xx1`
`rarr (8)^3-(6)^3xxrho=(1/2)(8)^3xx1`
`rarrrho=512/(2x(512-216))`
`=512/(2xx296)`
`=0.865gm/cc=865kg/m^3`