Final answer:
In Physics, if no external forces act on an object in horizontal motion, it maintains its velocity. Therefore, a soccer ball moving at a horizontal speed of 70 mi/h during the second second will also be moving at 70 mi/h during the third second, given no air friction.
Step-by-step explanation:
The subject of the question is Physics, and it pertains to the horizontal motion of a soccer ball during a game. Assuming no air resistance, an object in horizontal motion will maintain its velocity if no external forces are applied.
Since the ball's horizontal speed is given as 70 mi/h during the second second, it will continue to move at the same speed during the third second under ideal conditions, disregarding air friction. So, the ball will be moving at 70 mi/h horizontally during the 3rd second as well.
To find the horizontal speed of the ball during the 3rd second, we can use the fact that the motion of the ball is symmetric. This means that the horizontal speed during the 2nd second will be the same as the horizontal speed during the 3rd second.
Given that the horizontal speed during the 2nd second is 70 [mi/h], we can conclude that the horizontal speed during the 3rd second is also 70 [mi/h].