Question

The upthrust on block while floating is $Xkgf$. Find [$\frac{X-3}{2}$]. {Where , [] is a step function}

• A. $4$
• B. $5$
• C. $6$
• D. $7$

Answer 1

Answer: (B)

$5$

$m_B=13.5kg{v}_B=15\times {10}^{-3}{m}^3{\rho }_w=1000kg/m^3$
Density of block $={\rho }_B=\frac{m_B}{v_B}=\frac{13.5}{15\times {10}^{-3}}kg/m^3=900kg/m^3$
$\because {\rho }_B<{\rho }_w\therefore$ the block will float on water.
$\therefore$ upthrust on block = weight of block = $m_{B}g=13.5kgf$
Given that upthrust on block = $Xkgf$
$\therefore Xkgf=13.5kgf$
$\therefore \left[\frac{X-3}{2}\right]=\left[\frac{13.5-3}{2}\right]=\left[5.25\right]=5$