Consider an inertial reference frame.

In this coordinate system
1. nothing can accelerate.
2. there is no inertia.
3. objects with no forces acting on them
have no acceleration.
4. inertial mass depends on your elevation.

In an inertial reference frame, the following statements are true:

1. Nothing can accelerate: In an inertial reference frame, objects will either remain at rest or move with a constant velocity unless acted upon by external forces. This means that there are no net forces acting on objects, resulting in no acceleration.

2. There is no inertia: This statement is incorrect. Inertia refers to an object's resistance to changes in its state of motion, whether it be at rest or in motion. In an inertial reference frame, objects still possess inertia, as they require force to change their velocity.

3. Objects with no forces acting on them have no acceleration: This statement is accurate. In the absence of external forces, objects in an inertial reference frame will experience no acceleration. Newton's first law of motion states that an object will continue in its state of rest or in uniform motion in a straight line unless acted upon by an external force.

4. Inertial mass depends on your elevation: This statement is incorrect. Inertial mass refers to the property of an object that determines how it responds to applied forces. It is unrelated to elevation or height above the Earth's surface. The inertial mass of an object remains constant regardless of its position in an inertial reference frame.

http://www.freedictionary.org/?Query=inertial%20reference%20frame

And Newtons first law says that it takes a force to change motion (ie, accelerate an object).