Answer:
According to the Given Statement
Canon fires directly upwarda at 150m/s ( Initial speed, u )
Acceleration due to gravity is 10m/s²
Since Cannon ball reach it maximum height so its final velocity v will be 0 m/s .
Using Kinematic Equation
On substituting the value we get
➥ 0 = 150 + 10 × t
➥ 150 = 10 × t
➥ 150/10 = t
➥ 15 s = t
So, it will take 15 seconds .