Question

In which of the following frames does Newton’s 1st law of motion apply (There is no change in motion without force)?

The upper surface of a plank translating on a floor with friction)
The horizontal plane of an accelerating lift )
The vertical plane of an accelerating lift )
A braking bus)

Answer 1

Newton's Law "does not apply" to the horizontal plane of an accelerating lift - all of the others must obey the first law