If a baseball were thrown at an infinite velocity on a line drive, it would result in a situation that is not physically possible. In reality, it is impossible for any object with mass to reach or exceed the speed of light, which is the fundamental speed limit of the universe according to our current understanding of physics.
However, let's consider the hypothetical scenario where a baseball could somehow attain an extremely high velocity close to the speed of light. At such speeds, the laws of physics, particularly those described by Einstein's theory of relativity, would come into play and have significant effects on the behavior of the baseball.
As an object approaches the speed of light, its mass would increase according to the relativistic mass-energy equivalence equation (E=mc²). This means that the baseball's mass would become virtually infinite, requiring an infinite amount of energy to accelerate it further. Such a scenario is beyond the realm of physical possibility.
Additionally, as an object approaches the speed of light, time dilation occurs. Time would appear to slow down for the baseball relative to an observer at rest. This means that, from the perspective of a stationary observer, it would appear that an infinite amount of time would be required for the baseball to reach such speeds.
In summary, the concept of a baseball being thrown at an infinite velocity is not feasible within the bounds of our current understanding of physics. The laws of nature, particularly those related to the speed of light and relativistic effects, prevent objects with mass from reaching or exceeding the speed of light.