Questions tagged [relative-motion]
Use this tag for questions related to how objects move relative to other objects dependent on your frame of reference, and how this applies to special relativity.
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questions with no upvoted or accepted answers
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Sum of geodesic deviation around a triangle in curved spacetime?
So I was pondering about geodesic deviations and I'm confused about the following. Let's say I have $3$ geodesics $\gamma_1(t)$ , $\gamma_2(t)$ and $\gamma_3(t)$. I introduce a parameter $s$ such that ...
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How to derive relative velocity in two particle scattering?
While calculating the scattering cross section for one particle scattering we use the formula $$J_i=\rho v$$ where $\rho$ is the density of the incoming beam and $v$ is the velocity of the incoming ...
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Scalar versus invariant in Newtonian mechanics
I looking up coriolis transport theorem for rotating refrence frames and while reading through this derivation he wrote:
In Newtonian mechanics, scalar quantities must be invariant for any
given ...
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Upstream and downstream problem using relative velocity
On a river coast, there is a port; when a barge passed the port, a motor boat departed from the port to a village at the distance $S_1 = 15$ km downstream. It reached its destination after $t = 45$ ...
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Should the velocity increase or decrease?
Suppose some projectile is traveling along the positive $x$ direction at a velocity $v$. While moving it is emitting particles, and thus losing mass. If the particles are being emitted in the same ...
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Would impact angle matter on relativistic impactor?
I'm trying to calculate (for fun) a comparison between a kinetic impactor and an H-bomb.
I would assume this to be a fairly straight forward problem involving kinetic energy and a table of various H-...
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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). ...
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Coordinate transformation and absolute motion in general relativity
In special relativity, all motion is relative. But in the presence of black hole, all motion is with respect to black hole. The curvature of spacetime depends on how far we are away from the black ...
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Attempting to solve the twin paradox without acceleration
My teacher told me that the key to solve the twin paradox is acceleration of the one that travel away. However, I feel a little bit uncertain that time change significantly by just a slightly nudge of ...
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answer
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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,...
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vote
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answer
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Relative velocity and proper time derivative of geodesic deviation?
From wiki
To quantify geodesic deviation, one begins by setting up a family of closely spaced geodesics indexed by a continuous variable s and parametrized by an affine parameter $\tau$. That is, for ...
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Is e (COR) defined for whole situation or just during collision
According to wikipedia
$${\text{Coefficient of restitution }}(e)={\frac {\left|{\text{Relative velocity after collision}}\right|}{\left|{\text{Relative velocity before collision}}\right|}}$$
...
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vote
1
answer
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Linearly Interpolating in a Non-Inertial Frame
I am working on an engineering task where we have a flying object which knows its height above a curved surface as well as how close it is to other flying objects. If I want to interpolate between two ...
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Work done on a moving cart in wind
Let us suppose a cart is moving in a rough ground with a propeller attached to the roof of the cart.
Let the velocity of the cart at the given point of analysis be V and velocity of wind is -W. The ...
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vote
0
answers
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How does motional EMF emerge from Jefimenko's Equations?
I have been using Jefimenko's Equations for determining the electric and magnetic fields of a conductive coil with a (possibly changing) current. For most situations of interest this can be done to ...
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1
answer
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Swing in moving truck
I was just thinking about a situation in which a big truck is moving in high speed say ( $80 \ miles/hr$). There is a swing attached with the ceiling of the truck container which can move freely in ...
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answer
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Kinematics in moving reference frames
Assume we have an object moving along a path $p_W(t)$ that is described in some fixed reference frame $W$. If we now have a second reference frame $B$ which differs from $W$ by some time varying ...
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Vector addition of drone affected by wind
I've been struggling with this calculation for around a week and am starting to question whether or not it's even possible.
What I want to do is find the bearing and speed a drone will need to fly at ...
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Why does the equation for transformation of relative acceleration from one non-inertial system to another involve absolute angular velocities?
It seems that the equation for transforming between two different expressions of the relative acceleration of a vector involves absolute angular velocities, which I find surprising.
Consider two non-...
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Curved space relative motion
Suppose I live in a 2d curved space. I can describe intrinsically the motion of a particle which moves in my 2d manifold using time "t" as a parameter.
Now suppose there is a second observer (let's ...
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Relative velocity and pseudo forces
If I am in a spaceship moving in deep space....... which is accelerating.... There is nothing around to compare my motion with.... How can I say even if I'm moving or not....if I say I experience a ...
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Are there local coordinates for Schwarzchild spacetime?
In the Schwarzchild metric, $t$ is the time on the clock of an observer at infinity, and $r$ is the related to the area of a sphere by $A=4\pi r^2$. Are there more physical coordinates one could use, ...
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Correlation between velocity and homogeneity of spacetime and isotropy of space
Considering only inertial frames of reference and constant velocities, does the fact that any velocity, with the exception for the speed of light in a vacuum, can be transformed, via an accurate ...
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Zero longitudinal momentum in Special Relativity
A particle is moving with an arbitrary momentum $p$ in K-reference frame. According to Jackson, "there is a unique Lorentz transformation in the $z$-direction to a frame K' where the particle has no $...
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Can the Doppler effect account for the increase in an object's energy with velocity?
I am aware that the relativistic mass can be expressed in terms of rest mass and momentum, which seems to be the canonical explanation, but I am looking at an alternative way of visualising the ...
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Relative Motion Question - Inparticular method
Here is my question:
Aircraft A is travelling
West and aircraft B is flying in a circular, anti-clockwise holding pattern of 2km radius at 400 km/h. When ‘B’ is pointing South, the pilot ...
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0
answers
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Is there some kind of aether for rotations only?
Currently I'm reading "A briefer history of time". I understand how the Michelson–Morley experiment refutes the theory of an aether (like in "absolute frame of reference") for translation in space and ...
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Force impact when lifting objects traveling at a relative velocity of 0
During a break my colleagues and I came up with the following Gedankenexperiment I would appreciate if you guys helped us find the solution for:
Truck (weight 5t) traveling at 80 kph with a tow-truck ...
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vote
0
answers
136
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Wind resistance on moving body
Suppose that a vehicle is traveling 60 km/h north, and the wind speed is also 60 km/h going the same direction, would there be wind resistance, and to what extent? Also, if I put my hand outside the ...
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1
vote
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answer
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Speed with wind resistance
This is probably a basic question, but it has been a while since I did anything like this.
If a boat is sailing forward at speed $x$ and the direction of the wind, with magnitude $y$, is either equal, ...
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