I was going through this answer which beautifully explains why free falling objects are in an inertial frame of reference. This is the example that was given to explain why observers in a non-inertial frame observe a fictitious force:
For example, consider the case of two observers, one who is at rest on the ground and the other who is in an accelerated car(say moving in the positive x-axis with constant acceleration) that is passing by the observer resting on the ground. The observer in the car will discover a very peculiar situation in his frame of reference, when he holds his medal by a string, he immediately observes that the medal starts to move backwards in the negative x-direction and the string that is holding the medal makes an angle with the vertical. If he has a ball in his hand and lets it go, he observes that the ball starts to accelerate backwards(negative x-direction) until it hits the back of his car. So it appears as if there is some mystical force in this observer's frame that has no obvious origin, which acts upon all objects and accelerates them backwards. This observer will further note that this mystical force is proportional to mass, or in other words, the acceleration of any object is independent of it's mass, so that if you hold two different masses in your hand and let them go, they will hit the back of the car at the same time. But the observer who's at rest on the ground will object! he will argue(rightly) that there is no mysterious force that is accelerating the objects in the car. The fact that any object "appears to accelerate" backwards is a simple consequence of these two following facts:
1)The car is accelerating onward in the positive x-direction.
2)The objects, when they are let go, they are moving with constant velocity(they both have the same velocity) in the positive x-direction according to the ground observer, and following Newton's first law, they will continue to do so, but the car is still accelerating onward, so they eventually hit the back of the car at the same time.
Now let's take an example of a person jumping from a tower. While the person is standing on the tower he is also in an non-inertial frame of reference like the person sitting in the car in the above example, similarly when the person jumps, his state is similar to the ball let go inside the car. My question is, unlike the ball that hits the back of the car, the person will always fall towards the earth. Why doesn't one of following happen ->
- The person hitting the side of the tower.
- The earth moving away from the person and him ending up in space.
