Question

A block of density 2000 $kg/m^3$ and mass 10 kg is suspended by a spring stiffness 100 N/m. The other end of the spring is attached to a fixed support. The block is completely submerged in a liquid of density 1000 $kg/m^3$. If the block is in equilibrium position then,

• A. the elongation of the spring is 1 cm.
• B. the magnitude of buoyant force acting on the block is 50N.
• C. the spring potential energy is 12.5 J.
• D. magnitude of spring force on the block is greater than the weight of the block.

Answer 1

Answer: (B), (C)

The correct options are
B the magnitude of buoyant force acting on the block is 50N.
C the spring potential energy is 12.5 J.

At equilibrium
$kx=Mg-F_{B}kx=mg(1-\frac{\sigma }{p})\Rightarrow 100\left(x\right)=100(1-\frac{1000}{2000})\Rightarrow x=0.5m{F}_B=50NP.E.=\frac{1}{2}k{x}^2=12.5J$