Answer:
7 m/s
Explanation:
To solve this problem you must use the conservation of energy.
That math speak for, initial kinetic energy plus initial potential energy equals final kinetic energy plus final potential energy.
The initial PE (potential energy) is 0 because it hasn't been raised in the air yet. The final KE (kinetic energy) is 0 because it isn't moving. This gives the following:
K1=U2
Solve for v
Input known values and you get 7 m/s.