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Question:
A $60 \mathrm{~kg}$ man skating with a speed of $10 \mathrm{~m} / \mathrm{s}$ collides with a $40 \mathrm{~kg}$ skater at rest and they cling to each other. Find the loss of kinetic energy during the collision.
Solution:
$m_{1}=60, v_{1}=10, m_{2}=40, v_{2}=0, V=v_{\text {final }}$
Use C.O.L.M
$60 \times 10+0=(60+40) \mathrm{V}$
$V=\frac{600}{100}=6$
$\Delta K \cdot E_{\text {loss }}=\left|\frac{1}{2} \times 100 \times 6^{2}-\frac{1}{2} \times 60 \times 100\right|$
$\Delta K . E_{\text {loss }}=\left\lfloor\frac{1}{2} \times 100 \times 6^{2}-\frac{1}{2} \times 60 \times 100\right\rfloor$
$=|1800-3000|$
$=1200 \mathrm{~J}$
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