Question

An one of mass 2.1 kg is immersed in a liquid of density $1.8g{cm}^{-3}$. If the density of the one is $6.3\times {10}^{3}kg{m}^{-3}$, find the upthrust if kgf.

• A. $6.2$
• B. $6.0$
• C. $0.4$
• D. $0.6$

Answer 1

The correct option is B $6.0$

$\begin{array}{c}\text{Given that, mass of one}=2\cdot 1kg\\ \text{density of one}\left(\sigma \right)=6.3\times {10}^{3}kg/m^3\\ \text{density of liquid}\left(\rho \right)=1.8g/{cm}^3=1.8\times {10}^{3}kg/m^3.\end{array}$

$\begin{array}{cc}\text{Upthrust = Buyount force}& \\ =\text{PVg ... where}& \text{P=liquid density}\\ \begin{array}{cc}V& =\text{volume of one.}\\ g& =\text{gravity.}\end{array}& \end{array}$

$\begin{array}{cc}\text{Volume of one}\left(V\right)& =\frac{\text{mass of one}}{\text{densty of one}}\\ & =\frac{2.1}{6.3\times {10}^3}\\ \therefore \text{Upthrust}& =1.8\times {10}^3\times \frac{2.1}{6.3\times {10}^3}\times 10\end{array}$

Upthrust $=6\cdot 0$

Hence Option B is correct