Why do Newton's laws only apply in inertial reference frames?

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SUMMARY

Newton's laws of motion, specifically the first law, apply exclusively in inertial reference frames, which are defined as frames moving at constant velocity. In contrast, non-inertial reference frames, such as one experiencing acceleration, do not adhere to this law. Concrete examples include tossing a ball in space (inertial frame) versus tossing a ball on Earth (non-inertial frame), where the ball's trajectory curves due to the Earth's acceleration. A pool table serves as a practical example of an inertial frame in the xy plane, where a ball moves straight until affected by friction.

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  • Understanding of Newton's laws of motion
  • Familiarity with concepts of inertial and non-inertial reference frames
  • Basic knowledge of motion and trajectories
  • Awareness of the effects of friction on moving objects
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Hello, I am having difficulty understanding the concept of Newton's first law only applying in an inertial reference frame, or a frame that is at constant velocity, however, apparently the 1st law no longer applies if the reference frame is accelerating. Can anyone give me some sort of concrete example so I can see it in my mind, right now it's not making any sense to me. Actually, I just need an explanation of the whole concept of inertial vs noninertial reference frame.
 
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If you're floating out in space that's an inertial frame. If you toss a ball it will go straight at a constant velocity.

In contrast a non-inertial frame is where you're standing on the Earth and you toss a ball the ball travels in a curve.

A pool table simulates an inertial frame in the xy plane ie z is height above the ground. Setting a ball in motion it will move straight and only slow due to friction.
 

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