Answer
48.77 J
Work Step by Step
The sum of the translational and rotational kinetic energy makes the total kinetic energy. The angular velocity is given by $\omega=\frac{v}{R}$. The rotational inertia of a sphere about an axis through its center is $I=\frac{2}{5}mR^2$.
$$KE_{total}=KE_{transl}+KE_{rot}=\frac{1}{2}mv^2+\frac{1}{2}I\omega^2=\frac{1}{2}mv^2+\frac{1}{2}(\frac{2}{5}mR^2)\frac{v^2}{R^2}=\frac{7}{10}mv^2=(0.7)(7.25kg)(3.1m/s)^2=48.77J$$
