In a perfectly inelastic collision, two spheres made of the same material with masses 15 kg and 25 kg, moving in opposite directions with speeds of…

In a perfectly inelastic collision, two spheres made of the same material with masses $\displaystyle 15$ kg and $\displaystyle 25$ kg, moving in opposite directions with speeds of $\displaystyle 10$ m/s and $\displaystyle 30$ m/s, respectively, strike each other and stick together. The rise in temperature (in $\displaystyle { }^{\circ} \mathrm{C}$ ), if all the heat produced during the collision is retained by these spheres, is : (specific heat of sphere material $\displaystyle 31 \mathrm{cal} / \mathrm{kg} .{ }^{\circ} \mathrm{C}$ and $\displaystyle 1 \mathrm{cal}=4.2 \mathrm{~J}$ )