Final answer:
To find the distance from the tennis player to the wall, the time taken for the echo to return (0.4 seconds) is halved, and then multiplied by the speed of sound (330 m/s), revealing that the wall is 66 meters away.
Step-by-step explanation:
To determine the distance a tennis player is from the wall when they hear an echo 0.4 seconds after hitting a ball, we use the concept that sound travels at a constant speed in a given medium. The speed of sound in air is given as 330 meters per second. When a sound is produced, it travels to the wall, reflects off of it, and then travels back to the person. The total time for this journey is 0.4 seconds. Since this includes the trip to the wall and back, we divide this time by 2 to find the time it took the sound to reach the wall. Then, we multiply the time to reach the wall by the speed of sound to find the distance to the wall.
The time to reach the wall is 0.4 seconds / 2 which is 0.2 seconds. The distance to the wall is then 0.2 seconds × 330 m/s which is 66 meters. Hence, the tennis player is 66 meters away from the wall.