The Earth: An Inertial Frame of Reference

In summary, the Earth can be considered an inertial frame of reference, but only in the Newtonian sense where gravity is a force and the Earth's rotation and orbit are disregarded. However, when considering the entire planet, its rotation and orbit cannot be ignored, especially for longer distances and time scales.
  • #1
manimaran1605
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How Earth is considered to inertial frame of reference?
 
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  • #2
The Earth can be considered an inertial frame of reference in the Newtonian sense, where gravity is a real force, and when you disregard it's rotation about its axis as well as its rotation about the Sun and the Sun's rotation about the Galactic center.
 
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I don't see how you could consider the whole Earth as an inertial frame of reference, but only a tiny part of it (or an object of its surface). As soon as you take into account the whole planet, you can't ignore the fact that it's moving, both transating and especially rotating.
 
  • #4
If the time and space scales of your motion are very short (e.g., throwing a ball over normal, human distances) then the trajectory will barely be affected by the Earth's rotation. Just imagine how far the Earth will have rotated under your ball during the time it was in the air.

If you're firing naval artillery shells that can fly for more than a minute and disappear over the horizon, then yes you need to consider the rotation of the earth.
 
  • #5


Earth is considered an inertial frame of reference because it follows the laws of inertia as described by Newton's first law of motion. This means that an object at rest on Earth will remain at rest unless acted upon by an external force, and an object in motion on Earth will continue to move in a straight line at a constant speed unless acted upon by an external force. In other words, Earth does not accelerate or decelerate on its own, and therefore, it can be used as a reference point for measuring the motion of other objects. Additionally, the laws of physics, such as the conservation of momentum and energy, hold true on Earth, further supporting its classification as an inertial frame of reference.
 

1. What is an inertial frame of reference?

An inertial frame of reference is a coordinate system in which Newton's laws of motion hold true and there is no net force acting on an object. In other words, an object in an inertial frame will either remain at rest or move with a constant velocity unless acted upon by an external force.

2. How is the Earth considered an inertial frame of reference?

The Earth is considered an inertial frame of reference because, despite its rotation and revolution around the sun, the Earth's motion can be approximated as uniform and unchanging. This allows for the use of Newton's laws of motion to accurately describe the behavior of objects on Earth.

3. What are some examples of non-inertial frames of reference on Earth?

Some examples of non-inertial frames of reference on Earth include a car accelerating or decelerating, a rollercoaster moving along its track, or a person standing on a moving train. In these situations, Newton's laws of motion do not hold true and the motion of objects in these frames will appear to be affected by fictitious forces.

4. How does the Earth's rotation affect inertial frames of reference?

The Earth's rotation causes a centrifugal force that is often considered a fictitious force in inertial frames of reference. This force is only apparent in non-inertial frames, such as standing on the Equator, and can have a small effect on objects in these frames.

5. How does the concept of an inertial frame of reference relate to Einstein's theory of relativity?

In Einstein's theory of relativity, the concept of an inertial frame of reference is expanded to include the idea that the laws of physics should appear the same to all observers in any inertial frame, regardless of their relative motion. This led to the development of the theory of general relativity, which explains how gravity affects the motion of objects in inertial frames.

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