Statement

$21.$ ### Problem Statement

$4.2.21^*.$

a. A wooden cylinder with a radius of $1\mathrm{~m}$ and a height of $0.2 \mathrm{~m}$ rises to the surface from a depth of $1$ m in a body of water. The density of the wood is $0.8 \cdot 10^3 \mathrm{~kg/m^3}$. How much heat will be released by the end of the motion of the water and the cylinder?

b*. A cylindrical plug with a radius of $r$ and a height of $h$ falls into a cylinder with a radius of $R$, partially filled with liquid. The initial height of the lower surface of the plug above the liquid level is $H$, and the initial velocity is zero. How much heat will be released by the end of the motion of the liquid and the plug? The density of the plug is $\rho$, and the density of the liquid is $\rho_0 > \rho$.