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1)A particle is found to be at rest when seen from a frame S1 and moving with a constant velocity when seen fron a frame S2. mark out the correct options
a)both are inertial frames
b)both are non-inertial
c)S1 is inertial,S2 is non-inertial
d)S1 is non-inertial ,S2is inertial
2)A particle atays at rest as seen in a frame. We can conclude that
a)frame is inertial
b)resultant force on tthe particle is zero
c)the frame may be inertial but the resultant force ion the particle is zero
d)the frame may be non-inertial but there is a non-zero reultant force
plz give the reasons also
Comments (13)
To answer both these questions, we need to know whether or not the particle is an isolated one, i.e. to say whether or not some more particles are present with whom the given particle can interact.
Generally, when one talks about a particle, it is assumed that it is isolated (until and unless, its given otherwise). Now an isolated particle can only move with a constant velocity as seen from an inertial frame. In fact, this fact is used to define an inertial reference frame.
For the first question, using the above fact, (a) must be correct.
Now, can you think of the second one?
The answer I think of is a bit different, if one doesn't take the isolated particle case. The frames(obviously) can be both inertial, and can't (again obviously) be one inertial and one non-inertial. But I think that both frames being NON-INERTIAL can also satisfy the conditions given. Take this picture as an example.
Let acceleration of P wrt Man be a.
Let acceleration of S1 wrt Man also be a.
Let acceleration of S2 wrt Man (again) be a.
All accelerations are in horizontal direction only, and are constant.
In this case, acceleration of P wrt S1 = 0.
And, acceleration of S1 wrt S2 = 0, implying that acceleration of P wrt S2 = 0.
Thus, if P and S1 start from rest at the same time, and S2 starts at any time, then P will be stationary wrt S1, and will be moving with constant velocity wrt S2.
Now, this is an example satisfying the given question’s conditions, but the observer on earth knows that S1 and S2 are both non-inertial reference frames. So what answer will he choose?
(The conditions will also be satisfied for two inertial frames as well.)
So, I think, the answers can be:
Either
(a)both are inertial frames
OR
(b)both are non-inertial frames.
Yeah I think the last answer makes sense...
If the partical, S1 and S2 have the same acceleration, then they can satisfy the given condition.
Live example:
you... Your own frame and that of a car at constant speed...
Now, We know that we are a non-inertial frame... we have an acceleration towards sun and all :)
So A and B both
I hope I didn't ignore anything
-Mayank Singhal
IIT Bombay
(Visit LOLLAND)
Qn 2 is meaningless. You can't answer anything about it unless you are referred to another frame, or unless the options are diferent, compatible with the information supplied.
As to no. 1, a seems to be the most suitable answer.
cos, see, since the particle is in eqm from both the frames, (net force in either case is 0), the only plausible options are that....
a.the frames are under 0-force conditions (ie inertial)
b.both frames are accelarating such that the pseudo force due to their motion just cancels net force on the particle.
now if b were true, it is easy to understand that it would be impossible for the particle to appear to be in two different states of motion when viewed from those frames.
clearly, a. is the only feasible option
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