A metal ball of mass $3 \mathrm{~kg}$ moving with speed of $108 \mathrm{~km} / \mathrm{h}$ has a hea

Question

A metal ball of mass $3 \mathrm{~kg}$ moving with speed of $108 \mathrm{~km} / \mathrm{h}$ has a head on collision with a stationary ball of mass $2 \mathrm{~kg}$. If after collision, both the balls move as a single mass, then the loss in K.E. due to collision is\

Professor PC Thomas Classes · Answer

(b) : $m_{1}=3 \mathrm{~kg}, v_{1}=108 \mathrm{~km} / \mathrm{h}=30 \mathrm{~m} / \mathrm{s}, m_{2}=2 \mathrm{~kg}, v_{2}=0$. Final velocity $V$: $V = \frac{3(30)}{3+2} = 18 \mathrm{~m} / \mathrm{s}$. Initial KE: $KE_i = \frac{1}{2}(3)(30)^{2} = 1350 \mathrm{~J}$. Final KE: $KE_f = \frac{1}{2}(5)(18)^{2} = 810 \mathrm{~J}$. Loss in K.E. $= KE_i - KE_f = 1350 - 810 = 540 \mathrm{~J}$.