All Questions
Tagged with relative-motion newtonian-mechanics
200
questions
1
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1
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57
views
Confusion about sign conventions used in the Doppler formula
Wikipedia gives the Doppler formula as:
$ f = \left( \frac{c \pm v_r}{c \pm v_s} \right) f_0 $
c is the propagation speed of waves in the medium.
$v_r$ is the
speed of the receiver relative to the ...
1
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0
answers
70
views
Does relative velocity apply before or after the impulse?
I'm solving the following question from Kleppner and Kolenkow:
My solution differs from the textbook solution not only in the magnitudes in parts (a) and (b) but also the conclusion in part (c). ...
0
votes
1
answer
44
views
The locus of the velocity vectors of a boat navigating in the sea under the presence of a very strong wind?
I already asked a question very similar to this one here and I think the solution would not work when the boat navigates in the sea when a very strong wind blows. That is I am trying to find the ...
0
votes
3
answers
84
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Conceptual meaning of frame of reference for kinetic energy
what does the statement
The speed, and thus the kinetic energy of a single object is frame-dependent (relative)
even mean? does the impact of a collision of moving bodies and henceforth transfer of ...
0
votes
2
answers
74
views
Accelerating body in a non-inertial frame of reference
If a body is subjected to a force, can I find a non-inertial frame of reference in which the body is not accelerating?
0
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0
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51
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Why is throwing a bullet by hands not effective as using a gun? [duplicate]
The bullet when fired applies equal and opposite force to the Gun, (Newton's 3rd law)
Thus to keep the gun stable we apply some force which should be equal to the force applied by the bullet.
If we ...
1
vote
1
answer
75
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Principle of Relativity and the invariance of Newton's law in IRFs
Newton's law are form invariant under the coordinate substitutions:
$$
\tilde{x^{i}}=x^{i}+a^{i}
$$
This means that Newtons' equation of motion,
$$
F^{i}=m \frac{d^{2} x^{i}}{d t^{2}}
$$
(where $i=1,2,...
0
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2
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76
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In galilean relativity, is an observer assumed to be at rest only to simplify calculations, or is there a physical reason for this assumption?
I am a beginner in Physics and my teacher taught us "Relative Motion" yesterday. He said that the "Observer is assumed at rest." Is the observer assumed to be at rest only to ...
5
votes
2
answers
850
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Does kinetic energy rely on the observer mass too since velocity is relative?
There is no 'correct' inertial reference frame according to relativity. Objects are only 'in motion' relative to an arbitrary inertial reference frame. So let us take the following example. A person ...
2
votes
1
answer
110
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Flying mosquito problem [duplicate]
Let's say there is a car and its doors and windows are closed. Basically it is a closed space inside. There is a mosquito hovering right in the center of closed space of the car. While doing so the ...
1
vote
0
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37
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Is e (COR) defined for whole situation or just during collision
According to wikipedia
$${\text{Coefficient of restitution }}(e)={\frac {\left|{\text{Relative velocity after collision}}\right|}{\left|{\text{Relative velocity before collision}}\right|}}$$
...
1
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4
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94
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A problem Understanding how a two-body system of planets starts rotating around barycentre
Consider,We are Creating a Two-body system in free space,Where no other mass exists,Let's Take First Mass M1 and hold it,Now bring Second Mass M2,hold it up,Now we are giving a suddenly impulse To M1 ...
5
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5
answers
1k
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How is a change in KE the same in every inertial reference frame?
This is not about special relativity, so assume speeds are much less than $c$.
This article says a change in kinetic energy (KE) remains constant in all inertial reference frames.
So the kinetic ...
0
votes
1
answer
48
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Kinetic energy consistency
Suppose a vehicle 1 is on the top of another vehicle 2 (we can think of it like a big platform).
Imagine the following independent experiments:
Suppose that the top vehicle accelerates to a speed $...
7
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6
answers
2k
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Is it wrong to just say that things continue at constant velocity unless acted upon, as velocity is only relative?
Like when saying that people mistakenly thought things automatically slowed down after being thrown etc (accelerated), because that's just due to all the air or surface friction or gravity. Do you ...