IIT JEE , AIEEE Forum - Physics , Mechanics

sucess_seeker

A reference frame attached to earth

a) is an inertial frame

b) cannot be an inertial frame because the earth is revolving around a sun.

c) is an inertial frame because newton's laws are applicable in this frame

d) cannot be an inertial frame because the earth is rotating asbout its axis.

the correct option is b and d . Is the velocity of rotation of earth not constant . And if reference frame is attached to earth is non-inertial then how do we say reference frame attached to eartrh as constant?

aditya_arora04

Hi,

Look,

Earth has a constant angular velocity. Now, there is a centripetal accleration acting on everything present on earth towards the centre. So, it is a non-inertial frame.

Also, as the earth rotates around the sun, a centripetal acceleration is observed by evrything on earth towards the sun.

Hope you have got it !!!

elessar_iitkgp

The rotation of earth around its own axis makes it a non inertial frame, for if we are to observe the equilibrium of any particle in the reference frame of earth, we mus introduce pseudo force. The effect of earth rotation is the reason for the coriolis forces that are observed on any particle moving on earth's surface, when observed in the reference frame of earth. Look up the last solved problem in HC Verma's Circular motion. You will get a fairly good idea of coriolis forces from there.

A similar effect is caused by the rotation of earth around the sun.

Now as to why we treat the earth as inertial frame for most problems. First these effects can be neglected for most problems that we solve at +2 level. Second, the complexity of the problem increases twofold.
So for a simpler analysis, we neglect such effects & assume that Newton's Laws are applicable.

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