(a) Using the relativistically correct final velocities for the collision shown in Figure $2.21 a\left(v_{1 f}^{\prime}=-0.585 c, v_{2 f}^{\prime}=\right.$ $+0.294 c$ ), show that relativistic kinetic energy is conserved according to observer $O^{\prime} .$ ( $b$ ) Using the relativistically correct final velocities for the collision shown in Figure $2.21 b$ $\left(v_{1 \mathrm{f}}=-0.051 c, v_{2 \mathrm{f}}=+0.727 c\right),$ show that relativistic
kinetic energy is conserved according to observer $O$.