Final answer:
The optimal angle for the maximum projectile range is 45°. The range is zero at 0° or 90° for a projectile. A box's weight has a maximum perpendicular component on an incline at 90°.
Step-by-step explanation:
The optimal angle for a projectile to cover the maximum distance is 45°. This is because, at 45°, the projectile's range is maximized due to an equal distribution of the initial velocity in both the horizontal and vertical components. When a projectile's angle is 0° or 90°, its range is equal to zero.
For 0°, the projectile would move horizontally with no vertical component, and for 90°, it moves vertically upward and comes straight back down to the same point. The perpendicular component of a box's weight on an inclined plane is at its maximum when the plane is at an angle of 90°. At this angle, all the weight would be on the perpendicular component, acting directly downward against the plane.