All Questions
Tagged with relative-motion kinematics
171
questions
4
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5
answers
711
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Can't understand a statement about motion
From the book where I am studying motion, It says
Motion is a combined property of the object under study and the observer. There is no meaning of rest or motion without the viewer.
I know that, for ...
- 157
0
votes
0
answers
41
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Minimum seperation of moving objects doubt
Let there be $2$ objects $P_1$(initial velocity $u$ $ms^{-1}$ & acceleration $a$ $ms^{-2}$) & $P_2$ (initial velocity $U$ $ms^{-1}$ & acceleration $A$ $ms^{-2}$) initially separated by ...
0
votes
1
answer
282
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Angular velocity of a particle in uniform circular motion about a general point
This problem was given by our professor.
Consider a particle P executing uniform circular motion wrt the point O with uniform angular velocity $\omega$ anticlockwise whose cordinate is $(2R,0)$ in a ...
- 74
5
votes
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 ...
- 410
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 $...
- 31
0
votes
2
answers
153
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Average speed / Velocity
We know that in kinematics we have the concepts about "average speed". By definition the average speed is the total of the distance divided by time, but I still don't get it what is the ...
- 1
1
vote
1
answer
46
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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 ...
- 171
5
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3
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What is the "true" distance an object travels based on relative speeds?
There are two objects (x and y) with x travelling at 10km/h and y travelling at 11km/h, both with respect to the earth. After 1h, from the perspective of the earth, y travels 11km, but from the ...
- 59
3
votes
3
answers
515
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Relative velocity related to acceleration
Let's say we have a car moving on the horizontal ground with a velocity of $10 \hat{i} \frac{m}{s}$. A person inside throws a ball vertically upward with a velocity of $3 \hat{j} \frac{m}{s}$. Now I ...
- 169
0
votes
3
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239
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A question about relative motion and how to make sense of it
So, here is the question:
Assuming the 2D Cartesian system and the basis vectors $\hat{i}$ and $\hat{j}$, we have two cars A and B located at (0,6) and (-30,0) respectively. Car A starts moving with a ...
- 169
0
votes
2
answers
74
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Sign convention for relative displacment
If an object A is $X\ \mathrm m$ behind B,than the relative displacemnt of A wrt B would be $-X$. However is object A was moving towards B(at rest) at a rate of $Y\ \mathrm{m/s}$, then $$V_{ab}=+Y-0=+...
- 41
4
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3
answers
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Kinetic energy "paradox" -- where am I wrong here? [duplicate]
Body $A$ is at rest and has mass $2$, so the energy required in order to accelerate it to a speed of $v$ is $v^2$, and so the energy required in order to accelerate it to a speed of $2$ is $4$.
On the ...
- 143
0
votes
1
answer
95
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For an airplane moving north from some latitude (say $30^{\circ}N$), why does rotation of the Earth cause an increase in apparent drag?
I'm not able to understand the answer to this example:
Example 10 from the Curtis Orbital Mechanics text book :
An airplane of mass $70 000\ \mathrm{ kg}$ is traveling due north at latitude $30^\circ$...
0
votes
1
answer
76
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How do you find relative motion of two objects not travelling in a straight path?
I understand relative motion linearly, but how about more complex motion, like travelling in a circle? Would you just find the objects velocities at some point using the formula $v=\omega r$ and then ...
- 169
9
votes
3
answers
2k
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Greatest distance between a particle moving with constant velocity and a particle moving with constant acceleration
Two particles start moving along the same straight line starting at the same moment from the same point in the same direction. The first moves with constant velocity $u$ and the second with constant ...
- 309