The final velocity is m/s for a hollow spherical ball with mass of 0.03 kg that rolls (without slipping) down a slope with height of 12m.

Explanation:

Using conservation of energy

Change in potential energy is equal to change in kinetic energy

∆P.E = ∆K.E

The initial K.E is zero

The final potential energy is zero

mgh = ½mv²

m cancels out

gh = ½v²

v² = 2gh

v = √2gh

Given that h = 12m

g is constant = 9.81m/s²

v =√2×9.81×12

v = √235.44

v = 15.34 m/s

The final velocity is 15.34m/s

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.