Initial velocity, u = -6 m/s.
Time taken, t = 4 seconds.
Acceleration due to gravity, .( Here negative sign means downward direction )
To Find :
Velocity after 4 seconds.
Solution :
By equation of motion.
v = u + at
Here , a = g.
v = u + gt
v = -6 + (-9.8)×4
v = -6 + (-39.2)
v = -45.2 m/s
Therefore, velocity after 4 seconds is -45.2 m/s.
Hence, this is the required solution.