Final answer:
The ball takes approximately 4.08 seconds to stop.
Step-by-step explanation:
To determine how long it takes for the ball to stop, we need to first understand the motion of the ball. When a ball is thrown straight upwards, it experiences a constant acceleration due to gravity pulling it downwards. The initial velocity is 40 m/s. The final velocity when it stops momentarily is 0 m/s.
Using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time, we can rearrange the equation to solve for time t. In this case, u = 40 m/s, v = 0 m/s, and a = -9.8 m/s² (acceleration due to gravity).
0 = 40 + (-9.8)t
-40 = -9.8t
t = -40 / -9.8
t ≈ 4.08 s
Therefore, it takes approximately 4.08 seconds for the ball to stop. Since this is not one of the given options, we can conclude that none of the provided options, a) 1 sec, b) 2 sec, c) 3 sec, d) 4 sec, or e) 5 sec, is correct.