Question

You wake to find yourself in an airplane with all its windows covered. Is there any experiment you can perform to determine whether you are flying with a uniform velocity, or at rest on the runway? (Ignore external effects such as engine noises, which could be simulated as a diabolical plot to trick you.) If the airplane changed its velocity, could an experiment show this? If so, give an example of an experiment you might perform that could detect an acceleration of the airplane.

Answer 1

NO, according to the principle of relativity, all inertial observers are equivalent. If the plane is moving with a uniform velocity or is at rest, and then the person inside the plane, in both cases, will be an inertial observer. So he cannot determine motion of the airplane.

Inertial Observer : An observer, with respect to whom, Newton's first law of motion holds true.

YES, if one suspend a pendulum from the roof of airplane and if it becomes tilted with the normal through out the motion of the plane, the plane changing its velocity.