Final answer:
Given the same initial speed, the astronaut would catch the ball after about 7.3 seconds on the Moon because the Moon's gravitational acceleration is approximately 1/6th that of Earth.
Step-by-step explanation:
On Earth, an astronaut throws a ball straight upward and it stays in the air for a total of 3.0 seconds. On the Moon, assuming the astronaut throws the ball with the same initial speed, the duration the ball stays in the air would be longer because the Moon's gravitational acceleration is approximately 1/6th of that on Earth. We can calculate the time it takes for the ball to reach its peak height on Earth and use that to find the time on the Moon.
The total time in the air is 3.0 seconds on Earth, with 1.5 seconds to reach the highest point and another 1.5 seconds to return to the astronaut's hand. Since gravitational acceleration is 1/6th on the Moon, the ball takes √6 times longer to reach the peak and the same amount to return, making the total time 3.0 seconds × √6, which is approximately 7.3 seconds. Thus, the astronaut would catch the ball after about 7.3 seconds on the Moon.