Question

Two blocks of masses $10kg$ and $20kg$ moving at speeds $10m{s}^{-1}$ of and $20m{s}^{-1}$ respectively in opposite directions, approach each other and collide. If the collision is completely inelastic. Find the thermal energy developed in the process.

Answer 1

According to equation of conservation of momentum.

$(20{)}^2-(10{)}^2=30V$

$400-100=30V$

$300=30V$

$V=\frac{300}{30}$

$V=10$

From conservation of the energy.

$\frac{1}{2}[20\times (20{)}^2+10\times {10}^2]=H+\frac{1}{2}[30\times \left(10{)}^2\right]$

$\frac{1}{2}[8000+1000]=H+\frac{1}{2}\left(3000\right)$

$\frac{9000}{2}-\frac{3000}{2}=H$

$H=\frac{6000}{2}$

H = 3000 J

H = 3 KJ

So,

the thermal energy developed in the process is 3 KJ.