Final answer:
In projectile motion, the acceleration is never zero and is always directed vertically downward due to gravity. The acceleration is never in the same direction as a component of velocity and it is never opposite in direction to a component of velocity.
Step-by-step explanation:
(a) Is the acceleration ever zero?
No, the acceleration is never zero in projectile motion. The acceleration for a projectile is constant and always directed vertically downward due to gravity.
(b) Is the acceleration ever in the same direction as a component of velocity?
No, the acceleration is never in the same direction as a component of velocity. The acceleration always acts downward while the velocity has horizontal and vertical components.
(c) Is the acceleration ever opposite in direction to a component of velocity?
No, the acceleration is never opposite in direction to a component of velocity. The acceleration is always downward while the components of velocity can be upward or downward depending on the angle of projection.