Final answer:
The baseball thrown horizontally would have an initial vertical velocity of zero, because only gravity affects it after the throw, resulting in a vertical velocity of 29.4 m/s downwards after 3 seconds.
Step-by-step explanation:
The student's question pertains to the initial vertical velocity of a baseball that was thrown horizontally. Since gravity is the only force acting on the baseball in the vertical direction, we can use the kinematic equations to determine its initial vertical velocity. The initial vertical velocity is effectively zero since the ball has only horizontal velocity at the outset and no vertical component is given or implied. After 3 seconds, the vertical velocity would be due to gravity only.
Gravity acts downward on the baseball at an acceleration of approximately 9.8 m/s². Since the baseball is thrown horizontally, its vertical displacement starts at zero. Therefore, after 3 seconds, it would have a downward vertical velocity of 9.8 m/s² × 3 s = 29.4 m/s downwards, entirely due to gravity.