Question

Some iron beads are embedded in wax ball which is just floating in water. The volume of ball is $18 \,cm^{3}$ and relative density of wax is $0.9$. Then mass of the iron trapped in the ball is

• A. $1.8\, g$
• B. $2.7\,g$
• C. $16.8\, g$
• D. $8.1 \,g$

Answer 1

Answer: (A)

$1.8\, g$

Answer 2

Let mass of iron = m According to law of floatation Weight = upthrust (m + mass of wax)$g = 18 \times 1 \times g$ Ignoring the volume of iron since it is in the form of small beads $\therefore m+18 \times 0.9=18\times 1$ $m=1.8\,g$