Final answer:
In a car or airplane, the instinctive frame of reference is the vehicle itself, but we may also use the surroundings or Earth to sense and describe motion. Choice of frame of reference affects our perception of movement due to the relativity of motion.
Step-by-step explanation:
When driving a car or flying in a commercial jet airplane, we instinctively use different frames of reference. While inside the vehicle, our frame of reference is typically the car or airplane itself (option b), meaning we perceive motion relative to the interior of the vehicle. However, looking outside, we often switch our frame of reference to the surroundings, such as passing landscape or clouds (option c), allowing us to sense movement relative to these external stationary or moving objects.
A physicist might choose the Earth as a frame of reference for its properties as an inertial frame, where all forces have an identifiable physical origin and Newton's laws of motion are directly applicable. This contrasts with the car or airplane which are non-inertial frames of reference due to acceleration.
Motion is indeed a relative term and is perceived differently depending on the chosen frame of reference. This concept is crucial for correctly describing and understanding motion, direction, and speed of objects in dynamics and kinematics.