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

AI Thread Summary
Newton's first law applies only in inertial reference frames, where objects remain at rest or in uniform motion unless acted upon by an external force. In contrast, non-inertial reference frames, such as one that is accelerating, experience apparent forces that can alter the motion of objects. For example, when tossing a ball while standing on Earth, the ball follows a curved path due to the Earth's gravity and the acceleration of the frame. In an inertial frame, like floating in space, a tossed ball travels in a straight line at constant velocity. Understanding the distinction between these frames is crucial for grasping the principles of motion in physics.
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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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