Final answer:
When a projectile is fired from an inclined plane, it travels in a parabolic trajectory due to the combination of horizontal motion with constant velocity and vertical motion with acceleration due to gravity, leading to a parabolic path as the correct option.
Step-by-step explanation:
When a projectile is fired from an inclined plane at an angle θ with the horizontal, it travels in a parabolic path. This is because the motion of the projectile can be analyzed by breaking it into two independent one-dimensional motions along the vertical and horizontal axes, as described in projectile motion principles. The horizontal component of the velocity (βx) is constant since there is no acceleration in the horizontal direction (βx = 0). Conversely, the vertical component of the velocity (βy) is affected by the acceleration due to gravity,
As the projectile rises, its vertical velocity decreases until it reaches its highest point, at which the vertical velocity is zero. After reaching its peak, the projectile then falls back toward Earth, and its vertical velocity increases in magnitude but in the opposite direction. By combining these horizontal and vertical motions, the result is a parabolic trajectory. This dismisses the possibilities of the projectile traveling in a straight line, moving vertically upward, or moving at a constant speed in its entirety.
Using this understanding, we conclude that in an inclined plane at an angle θ with the horizontal, when a projectile is fired, it follows a parabolic trajectory with both horizontal and vertical components of motion until it impacts the ground. Hence, the mention correct option in final answer, it is 'B) It travels in a parabolic path'.