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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.

0 votes
1 answer
26 views

How to calculate the relative speed when three bodies are involved? [closed]

Two trains A and B start from a station and move in parallel tracks with velocities 40 kmph and 60 kmph respectively. A man sitting in train A. watches a lady who walks inside the train B at a speed ...
-5 votes
2 answers
57 views

What effect would relativity have for an objective with absolutely no momentum? [closed]

I know as you near the speed of light time slows down and mass increases to near infinite. What I'm curious about is what would happen if an object lost all momentum. No movement at all not even the ...
1 vote
2 answers
43 views

Straight wire in moving uniform magnetic field induced emf

My question is a follow-up to this one. The green dotted line is the arbitrary loop which is constructed in the calculation of emf in the wire of length L. x is a variable which can be changed to ...
0 votes
3 answers
75 views

Pseudo Orbital motion only due to Coriolis force

Planet, say of mass M and radius R is rotating with some angular velocity ω and a object of mass m (initially on the surface and rotating with the planet) was launched with velocity v vertically ...
3 votes
2 answers
277 views

Can we use relative motion if acceleration of two bodies are different?

Suppose, on the $x$-axis, a body $A$ is moving with velocity $v_1$ and acceleration $a_1$, and a second body $B$ is moving with velocity $v_2$ and acceleration $a_2$. $B$ is at a distance of $S$ from $...
0 votes
4 answers
325 views

A question about Lorentz force

According to standard electromagnetic theory, if the charge A is stationary and the charge B is moving along arbitrary trajectory then the electromagnetic force on charge A is: $$\vec{F}_A = q_A \left(...
-1 votes
0 answers
40 views

electromagnetism and special relativity [duplicate]

right now I am learning about special relativity, but like the VERY basics. i understand time dilation, length contraction, frames of reference all that but have not been introduced/understand the ...
1 vote
0 answers
69 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). ...
2 votes
3 answers
63 views

If an observer was trapped in a closed box with no way to interact with the external surroundings how will he know if he is moving or at rest [duplicate]

I am a high-school student. Recently we learned the concepts of relative motion and velocity. The idea that anything in motion can subsequently be at rest depending on the frame of reference ...
11 votes
3 answers
7k views

How can you accelerate without moving?

I know this question has been asked in other forms, generally regarding the balance of forces. This time I want to focus on motion. I've got a laser accelerometer on my desk. It tells me that I'm ...
3 votes
2 answers
1k views

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 $t = 45$ ...
103 votes
7 answers
112k views

Why does the atmosphere rotate along with the earth?

I was reading somewhere about a really cheap way of travelling: using balloons to get ourselves away from the surface of the earth. The idea held that because the earth rotates, we should be able to ...
-1 votes
2 answers
116 views

How Fast Must a Man Run to See Rain Falling horizontally?

The fact that tan 90° is undefined indicates a key issue in the problem. Does this mean it is impossible to observe rain falling at 90 degree? When rain is observed to be falling at 90° with the y-...
0 votes
0 answers
35 views

With what vel. would you have to launch an object vertically up from the earth's surface for it to land back again at it's initial launching point?

[Can skip reading this part] First of all, Newtonian gravity shall be considered whilst trying to solve this question. It's been on my mind for a long, long time and has been bothering me since. I ...
1 vote
0 answers
43 views

The stupidest question ever on relative kinematics and angular velocity [duplicate]

I am scratching my head on a very basic formula whose meaning escapes my intuition. On basically all texts of mechanics the following result is derived: Suppose that a rigid body is moving with ...

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