Final answer:
The coin thrown above a marked spot inside a plane will land inside the marked spot because the motion of the coin is relative to the plane, which is moving at a constant speed and altitude without any accelerations.
Step-by-step explanation:
If you throw a coin above a marked spot on the floor of a plane, the outcome of where it will land depends on the physics of relative motion. The motion of an object inside an airplane is relative to the airplane itself, assuming the plane is flying at a constant speed and altitude, without any acceleration. This concept is rooted in Newton's first law of motion, which states that an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
An observer inside the plane sees the coin fall straight down because both the observer and the coin share the same motion as the airplane. However, to an observer on the ground, the coin appears to move almost horizontally, maintaining the same forward velocity as the plane. Therefore, if you are a passenger on the plane throwing a coin above a marked spot, it will land inside the marked spot because the coin, you, and the airplane are all moving together.