Question

An object is dropped from a height of 25 meters. At what velocity will it hit the ground?

Answer 1

Data:
h=25 m
v₀=0 m/s
g=9,8 m/s²

we use this formula
h=h₀+v₀.t+(1/2).g.t²
25 m=0 m+0 m/s.t+(1/2).(9,8 m/s²).t²
25 m=4,9 m/s².t²
t²=25 m /4,9 m/s²
t²=5,1 s²
t=√(5,1 s²)=2,26 s 

Now, we calculate the última velocity 
v=v₀+gt
v=0 m/s+9,8 m/s².(2,26 s)=22,14 m/s≈22 m/s

solution: c.)  22 m/s