Why does a fly flies at the same speed than the car it is in?

Abatter hits the baseball a with an initial velocity of v0 = 110 ft/sec directly toward fielder b at an angle of 23° to the horizontal; the initial position of the ball is 2.2 ft above ground level. fielder b requires 0.44 sec to judge where the ball should be caught and begins moving to that position with constant speed. because of great experience, fielder b chooses his running speed so that he arrives at the “catch position” simultaneously with the baseball. the catch position is the field location at which the ball altitude is 8.4 ft. determine the velocity of the ball relative to the fielder at the instant the catch is made.

Achild throws a ball with an initial speed of 8.00 m/s at an angle of 40.0° above the horizontal. the ball leaves her hand 1.00 m above the ground. how long is the ball in flight before it hits the ground?

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?