Explanation

(c) In an inelastic collision, kinetic energy is not conserved but the total energy and momentum remains conserved.
[image:6_image60.emf]
Momentum before collision
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = Momentum\ after\ collision\ $
$m_{1}u_{1} + m_{2}u_{2} = m_{1}v_{1} + m_{2}v_{2}$
$\therefore\ \ \ \ \ \ \ \ \ \ 4 \times 12 = (4 + 6)v$
Or $v = 4.8ms^{- 1}$
Kinetic energy before collision $= \frac{1}{2}m_{1}u_{1}^{2}$
$= \frac{1}{2} \times 4 \times (12)^{2}$
$= 288J$
Kinetic energy after collision $= \frac{1}{2}\left( m_{1} + m_{2} \right)v^{2}$
$= \frac{1}{2}(10)(4.8)^{2}$
=115.2 J
Loss in kinetic energy=288 J-115.2 J
=172.8 J