An object is thrown upward with a speed of 14 m/s on the surface of planet x where the acceleration due to gravity is 3.5 m/s2. how long, in seconds, does it take for the object to reach the maximum height?

U = 14 m/s, g = 3.5 m/s². At maximum height, v = 0

v = u - gt

0 = 14 - 3.5t

3.5t = 14

t = 14/3.5

t = 4

time = 4 seconds

The maximum height of the object is where the final velocity becomes zero. The final velocity is obtained by,
                                  Vf = V1 - gt
Substituting the known values,
                                   0 = 14 m/s - (3.5 m/s²)t
The value of t is 4 seconds.