Inertial adn non-inertial frames

[jd12345]

i know these topics are discussed many times and i have read many of them but still have a doubt.

Suppose a car is accelerating and there is an object and a man in the car. Object is ofcourse at rest with respect to man. The man does not know if the car is accelerating or not - he just sees the object at rest. So for him the car is inertial frame and he can apply Newtons laws there . How would he know if he is in an non-inertial frame?

 

[pcm]

in car frame frictional force is acting on object ,still the object is at rest.so,it is obviously a non inertial frame.
for example, if he drops a ball it will not fall vertically downwards.

 

[A.T.]

So for him the car is inertial frame and he can apply Newtons laws there . How would he know if he is in an non-inertial frame?

By applying Newtons laws and comparing to reality. If applying Newtons laws (using only interaction forces) doesn't match experiments, then he knows is in an non-inertial frame.

 

[Creator]

i
Suppose a car is accelerating and there is an object and a man in the car. Object is ofcourse at rest with respect to man. The man does not know if the car is accelerating or not - he just sees the object at rest. So for him the car is inertial frame and he can apply Newtons laws there . How would he know if he is in an non-inertial frame?

Hate to tell you this jd, but even if the car is NOT accelerating, he is still in a 'non-inertial' frame simply because his butt is pressing against the seat due to gravity.

In addition if the car is accelerating horizontally (down the street) as you have said,then he can easily tell simply by hanging the object on a string from the ceiling of the car. If the object does NOT hang vertically, then he and the car are accelerating horizontally.

...

 

[PJC01]

The concept of inertial and non-inertial frames is a fundamental principle in the study of physics and is important in understanding motion and forces. An inertial frame is a reference frame in which Newton's laws of motion hold true, meaning that an object will remain at rest or in a state of uniform motion unless acted upon by an external force. On the other hand, a non-inertial frame is a reference frame that is accelerating or rotating, and therefore Newton's laws do not hold true in this frame.

In the example given, the man in the car may not be able to feel the acceleration of the car, but he can still determine if he is in a non-inertial frame by observing the behavior of the object. If the object appears to be accelerating or moving in a curved path, then the man would know that he is in a non-inertial frame. This is because in an inertial frame, the object would remain at rest or in a straight line due to its inertia.

Additionally, the man can also use other methods to determine if he is in a non-inertial frame, such as measuring the Coriolis force or observing the effects of fictitious forces like centrifugal force. These forces only exist in non-inertial frames and are not present in inertial frames.

It is important to understand the difference between inertial and non-inertial frames as it can greatly impact the accuracy of our observations and calculations. Inertial frames are necessary for the application of Newton's laws, while non-inertial frames require more complex equations to accurately describe the motion of objects. I hope this helps to clarify your doubts on this topic.