Final answer:
The vertical velocity of a tossed tennis ball decreases until it reaches its apex, then becomes negative as it falls, effectively reversing direction. Air resistance leads to a decrease in final velocity and kinetic energy. Vertical acceleration remains negative and constant. Option B is correct.
Step-by-step explanation:
When a tennis ball is tossed straight up, the vertical velocity changes throughout its flight. Initially, when the ball is thrown upwards, its vertical velocity is positive. As it ascends, gravity acts downwards so the velocity decreases until the ball reaches its maximum height at which point the velocity is zero.
After reaching the apex, the ball begins to fall, and its velocity increases in the negative direction (downward) until it hits the ground. Thus, the correct description of the ball's velocity is that it reverses direction; initially, it is positive, decreases to zero, and then becomes negative as it falls back to the ground.
Considering the GRASP CHECK, in the presence of air resistance, we would expect both the final velocity and final kinetic energy of the ball to decrease. This is because energy is dissipated as heat due to air resistance acting against the motion of the ball. Air resistance does not transfer energy to the ball, so both kinetic energy and velocity reduce.
The vertical acceleration of a ball in free fall remains constant regardless of the ball's motion in other directions. In this case, since the ball is being acted upon by gravity alone, its vertical acceleration is a negative constant value which represents acceleration towards the Earth. This is clearly described as a negative value that does not change with time.