Hi there!
We can solve this in two ways, using the Work-Energy theorem or kinematics.
Work-Energy:
We know that:
Ei = Ef, as long as there are no external forces working on the system.
Thus:
Ei = PE = mgh
Ef = KE = 1/2mv²
Therefore:
mgh = 1/2mv²
We can cancel out the mass:
gh = 1/2v²
9.8(10) = 1/2v²
√196 = v = 14 m/s
We can also solve using kinematics, using the equation:
vf² = vi² + 2ad
From rest (vi = 0 m/s) and a = g, so:
vf² = 2gd
vf = √2gh
vf = √(2 × 9.8 × 10) = 14 m/s
