Answer:
15 seconds
Step-by-step explanation:
Given that the initial speed of a cannon ball is 0.20 km/s. If the ball is to strike a target that is at a horizontal distance of 3.0 km from the cannon. The minimum time of flight for the ball can be calculated by using the formula for speed
speed = distance / time
Where
speed = 0.2 km/s
distance = 3 km
Substitute the two parameters into the formula
0.2 = 3 / t
make t the subject of the formula
t = 3/0.2
t = 15 s
Therefore, the minimum time of flight for the ball is 15 seconds