A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls

down a smooth surface to the ground, then climbs up another hill of height 30 m and

finally rolls down to a horizontal base at a height of 20 m above the ground. What is the

velocity attained by the ball .

I know to solve this problem we have to conserve energy .

That js potential energy = kinetic energy

But my doubtvis that in kinetic energy do we both of these ($\frac {1}{2}mv^2 + \frac {1}{2}I\omega^2$) or only $\frac {1}{2}mv^2$