How can a person trapped in a box figure out, without looking outside, whether the box is stationary or moving with a constant velocity?
Is it even possible, considering the fact that the box is an inertial frame of reference? (since acceleration, and thus net force, is zero)
Additional question: Assume that the box is moving with a constant velocity. When a ball is thrown at a wall, will the time taken by the ball to reach the wall be any different from the time taken when the box is stationary? (If I picture myself in a closed room, I don't see why this should be possible - yet I can't convince myself that this is the case. If the wall is moving away from the ball, it seems reasonable that the time taken should be more. Likewise, it feels reasonable to think that the ball should take less time to reach the wall that is moving towards it.)