Question

In which types of frames Newton's laws can be applied?

Answer 1

Unless acted on by a net external force, a body at rest remains at rest or, if in motion, continues in motion at constant velocity. The verb "remains" is used several times. This law might be seen as protecting the motion status quo. Also take note of the term "constant velocity," which signifies that the item maintains a straight line course since the magnitude and direction of the velocity vector do not vary.

Complete step-by-step solution:
In a frame of reference where a body travels at a constant speed, Newton's law may be applied. An inertial frame of reference is a frame of reference that does not accelerate in classical physics or special relativity. A physical object with zero net force acting on it moves at a constant velocity (which may be zero) in an inertial frame of reference—or, to put it another way, it is a frame of reference in which Newton's first law of motion holds. In analytical terminology, an inertial frame of reference is a frame of reference that characterises time and space homogeneously, isotropically, and time-independently.

With regard to one another, all inertial frames are in a condition of constant, rectilinear motion; an accelerometer travelling with any of them would record zero acceleration. A simple transformation can translate measurements in one inertial frame to measurements in another (the Galilean transformation in Newtonian physics and the Lorentz transformation in special relativity). In general relativity, one may identify a collection of inertial frames that roughly characterise any location small enough for the curvature of spacetime and tidal forces to be insignificant.
In classical and special relativity, the physics of a system alter depending on the acceleration of that frame relative to an inertial frame, and the conventional physical forces must be augmented with fictitious forces. Because of the notion of geodesic motion, systems under general relativity do not have external causes.

Note: Because the Earth is spinning, a ball put on the ground in classical physics does not fall exactly straight down, indicating that the observer's frame of reference is not inertial. To forecast horizontal motion, physics must account for the Coriolis effect—which may be thought of as a force in this situation. The centrifugal effect, or centrifugal force, is another example of a fictional force connected with spinning reference frames.