Final answer:
The motion of a truck with respect to an airplane is dependent on their relative directions of travel. If they are moving in the same direction, the truck appears to move in the same direction from the airplane's perspective. If stationary or moving oppositely, it appears stationary or in the opposite direction to someone in the airplane.
Step-by-step explanation:
The type of motion that a truck exhibits concerning an airplane depends on the relative directions they are moving in. If the truck and the airplane are moving in the same direction at any given time, then from the perspective of someone inside the airplane, the truck would appear to be moving in the same direction as the airplane, but at a different speed. It's important to note that this is assuming the truck is moving in a straight line and not changing its path to a circular or vertical one. On the other hand, if the truck is stationary or moving in the opposite direction of the airplane's motion, then it would either appear to be stationary or moving in the opposite direction from the viewpoint of someone on the airplane.
To expand on this with examples, imagine if a coin is dropped inside an airplane; someone in the plane would see it fall straight down, while someone on the ground would perceive it as moving almost horizontally (because of the plane's forward motion). Similarly, when a clod of dirt falls from a moving truck, it maintains the horizontal velocity of the truck relative to the ground. These principles apply due to Newton's first law, which states that an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.