A "K-9 cannon" launches a tennis ball vertically upwards
How long is the tennis ball in the air?
t = 5.1 [s]
Explanation:
To solve this problem, we can use the following equation of kinematics:
vf = vo - g*t
where:
Vf = final velocity = 0
Vo = initial velocity = 25 [m/s]
g = gravity acceleration = 9.81 [m/s²]
t = time [s]
By replacing the values:
0 = 25 - 9.81*t
t = 25/9.81
t = 2.54 [s]
The key to understanding this problem is that when the tennis ball is in the highest position, its velocity is zero. So, it will take the same time from the highest point to the ground.
t = 2.54 + 2.54
t = 5.09 [s]