Answer: 6.71 m/s
Explanation:
You can use either the energy conservation law (mechanical energy conservation principle) or the kinematic equations.
Let's see:
1) kinematic equations for free fall.
Vf² = Vo² + 2gy
Where Vo = 0 which implies Vf² = 2gy.
g is 9.38 m/s²
y = 2.3 m
∴ Vf² = 2 × 9.8 m/s² × 2.3m = 45.08 m² / s²
=> Vf = √ (45.08 m² / s²) = 6.71 m/s
2) mechanical energy conservation principle
a) Change in kinetic energy = change in gravitational potential energy
b) Change in kinetic energy = (1/2)m×Vf² - (1/2)m×Vo²
since Vo = 0, change in kinetic energy = (1/2)m×Vf²
c) Change in gravitational potential energy = m×g×h
∴ (1/2)m×Vf² = m×g×h
m in both sides can be cancelled => (1/2Vf² = gh => Vf² = 2gh, which is the same equation used in kinematics.
