The time rate of change of the position of an object

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1answer
38 views

Compute the minimal distance between two points in movement

There are two points, $A$ and $B$ that move according to these laws: $$ \vec{x_a}= 20 -10 t $$ $$ \vec{x_b}= -15 +15 t $$ $A$ moves along the x axis, $B$ along the y axis. I have to compute the ...
2
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3answers
170 views

Velocity measurement in relativistic perspectives

I understand the precepts of relativistic time dilation, but I'm looking to nail down the local perception of velocity in each frame. My question is threefold: Given two observers $A$ (rest frame) ...
2
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0answers
62 views

Relativity addition and signs

I have just covered a very brief module on special relativity as a part of my physics course. I have also done some extra reading mostly; Morrin's Classical Mechanics. While I found the book really ...
3
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3answers
883 views

Velocity of Voyager 1

I was reading Wikipedia which stated ....Voyager 1's current relative velocity is 17.062 km/s, or 61,452 kilometres per hour (38,185 mph)..... It travels away from sun. So sun's gravity must ...
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1answer
253 views

Small Animal Terminal Velocity

I recently saw a cat fall probably 100 feet like in this video Cat Falls. It seemed as if the cat reached terminal velocity by the time it hit. Does this mean that cats (and other small animals) could ...
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2answers
167 views

Ground velocity of satellite

I was wondering whether there is a simple formula in order to calculate the ground velocity (the velocity with which the satellite is moving along the planet's surface) on basis of the orbital ...
0
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1answer
109 views

Relativistic addition of velocities of spaceships

If Spaceship 1 is traveling at speed $.5c$ relative to Earth, and Spaceship 2 is traveling at speed $.3c$ relative to Earth in the same direction, what does Spaceship 2 see Spaceship 1's speed as? I ...
0
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2answers
102 views

Newton's Second Law

Newton's Second Law tells us that $\sum F = ma$. The vector sum of the forces $F$ on an object is equal to the mass $m$ of that object multiplied by the acceleration vector $a$ of the object. So ...
0
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1answer
54 views

velocity in inertial and nontial frames

I got confused about the difference between the last term of both pictures. In the first one, we have w x r, but in the second we have w x r underlined. Does anyone have a better explanation? They ...
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2answers
52 views

Query into the cumulative velocity of mounted platforms

Consider throwing a stone at an object from rest, it travels at Vms-1. Now throw that stone whilst running at Ums-1. It seems in the latter scenario the total speed of stone is V + U. Now imagine ...
4
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2answers
121 views

The velocity of a cloud?

I noticed an unusually fast moving cloud this morning. My questions: What is the average velocity of a cloud on Earth? What is the greatest ever recorded cloud velocity? What factors affect the ...
2
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3answers
398 views

Does mass affect velocity when travelling through frictionless medium?

I found the following question on an standardized test, and was debating with some friends what the answer would be: A car of mass M is travelling with a constant velocity through a plane in which ...
1
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1answer
83 views

Spinning theoretical object moving faster than the speed of light [duplicate]

Let's say you have the Earth, or any celestial body, spinning as it is. What if you build a tower from the surface, and extended it out into space. If it was built far enough, could the furthest end ...
0
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1answer
184 views

Finding release angle and final velocity of projectile when the target has a different coordinations [closed]

I am trying to write some codes for auto-snowball mechanism which seems like a regular projectile but instead of hitting the targets on the ground it is going to be able to hit the target in the air ...
0
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3answers
466 views

How does one measure velocity in space?

Just what the title states. Velocity, by definition, is the distance covered in a defined amount of time. How does one measure the velocity of a spacecraft that is not in Earth Orbit? E.g. Beagle ...
3
votes
1answer
439 views

Two vehicles moving in a line with different accelerations

Let two similar vehicles starting at rest in a straight line (with a distance of $D$ between them) have time-varying accelerations in the same direction. If both of them have similar time varying ...
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4answers
722 views

Time Dilation at zero velocity (and zero gravity)

From what I've learned, the more an object travels closer and closer to the speed of light, the more time will slow down for that object.. at least from an outside perspective.. It was shown that ...
13
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7answers
4k views

How can kinetic energy be proportional to the square of velocity, when velocity is relative?

Let's start with kinetic energy (from los Wikipedias) The kinetic energy of an object is the energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a ...
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1answer
130 views

Determine the distance from time-velocity graph [duplicate]

A small car that we made in class was travelling and its time was recorded at 1,2,3, and 4 meters. The points in the form (seconds, meters) are as follows: ...
0
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0answers
83 views

Calculating impact velocity and time with non-uniform acceleration [duplicate]

Here goes: imagine a spacecraft with engines shut off in a free fall towards some celestial body x. let's say the distance to surface is $100 000$ $\text{meters}$. initial vertical velocity is ...
0
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1answer
48 views

Recession of galaxies

when you take such a given galaxy and it is said that you are moving away from us with a speed $v$, what do you mean really? Let me explain: is the galaxy itself which has an intrinsic velocity of ...
0
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0answers
35 views

The average value of the the square of Dirac velocity operator

Let's have Dirac velocity operator (the case of the free particle: $$ \hat {\mathbf v} = i [\hat {H}, \hat {\mathbf r}] = \hat {\alpha}, \quad \hat {H} = (\hat {\alpha} \cdot \hat {\mathbf p}) + \hat ...
0
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2answers
213 views

Weird case for relative velocities and special relativity

This has bothered me for a while. I've been taught that the formula for determining the perceived velocity on an object from another moving object's reference frame under special relativity is: $$v = ...
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1answer
74 views

Does an aircraft hover at a constant acceleration or varied acceleration?

I have a question that's bugging me. Googling it only made me more confused so I really hope someone can help me clear this. If a plane is flying up and down; or hovering (Like the x-wing scene from ...
0
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1answer
103 views

What happens if a body free-falls at a certain speed?

It is known that a body falling to the ground is affected by gravity, and its velocity increases by 9.8 m/s per second. But when this body is falling, and it reaches the speed of 340 m/s (the speed of ...
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1answer
733 views

Calculating the energy of an electron given the wavelength

Okay, so I know that the wavelength of an electron is 5e-7m and I am asked to calculate its minimum velocity and hence minimum energy. Calculating the minimum ...
5
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2answers
631 views

Zeno’s Paradox of the Arrow

Premises And the Conclusion of the Paradox: (1) When the arrow is in a place just its own size, it’s at rest. (2) At every moment of its flight, the arrow is in a place just its own size. (3) ...
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0answers
14 views

Did a racer on a “restless” course race at some particular average velocity? (2: Starting gate and finish line being rigid to each other)

Consider two participants, a starting gate ($A$) and a finish line ($B$), in a (sufficiently) flat region, both undergoing uniformly accelerated motion, such that $A$ finds constant ping duration ...
5
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3answers
248 views

Physical intuition for independence of components of velocity in derivation of Maxwell–Boltzmann distribution

Maxwell derived the shape of the probability distribution of velocity of gas particles by starting with just two assumptions. These are: The probability distribution is rotation invariant. The ...
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2answers
7k views

Flow of liquid among branches

If water is flowing through big pipe is branched into 4 branches of small pipe. Lets say the flow is around 4 m/sec. I have the following questions: What will be the flow rate in each of the ...
0
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0answers
20 views

Did a racer on a “restless” course race at some particular average velocity? (1: Starting blocks, finish line moving uniformly wrt. each o.)

Consider two participants, $A$ and $B$ moving uniformly wrt. each other; first having approached each other, then having met and passed each other, and eventually having separated from each other such ...
0
votes
1answer
158 views

Finding an equation to solve for the velocity of a swimmer crossing a river [closed]

Where $\theta=45^\circ$, $d_1=200\:\mathrm{m}$, and $d_2=150\:\mathrm{m}$. I do not know how to combine the following equations: $$\begin{align} t&=\frac{d_1}{v_s\cos(45^\circ)}\\ ...
0
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1answer
31 views

Shock Absorber - Bus - Not Uniform

Imagine a empty bus/lorry travelling at high speed over the "speed brake", why is that only rear seat is heaved relatively high compared to the fron seat?
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2answers
208 views

How can I calculate the initial velocities of a set of objects with a consistent force?

I'm trying to figure out which object would have the largest time of flight when launched from a slingshot. To do this, I need the initial velocity. How can I calculate this if I know the mass and ...
6
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6answers
4k views

If an object moved 5 meters in a second, how can its velocity be 10 m/s?

I am reading the tutorial on physics classroom.com, and am at Meaning of Slope for a v-t graph. It gives data for an object experiencing an acceleration: This is the corresponding chart for the ...
0
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3answers
94 views

Question about relative speeds on a different “scales of perception”

I was kind of puzzled yesterday when thinking about this. If we observe an object moving away from us with 10m/s we would say the object is moving away from us really slowly But if we (humans, ...
1
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1answer
440 views

Velocity of real gas molecules?

It is known that the velocity of ideal gas molecules can be computed using Maxwell-Boltzmann law of distribution of molecular velocities, with average velocity given as: ...
1
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2answers
50 views

Final position of an object after aplying several horizontal forces [closed]

I'm given an object with a starting position. Several horizontal forces are applied to this object one after the other for different amounts of time. How can I determine the final position $x$?
-2
votes
1answer
74 views

Finding the constant of gravity in a game [closed]

Minecraft is a game of mining where one digs and finds ore (to put it simply). the world is composed of "blocks" 3 dimensional cubes that have different "pictures" on them, that make them appear like ...
2
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2answers
327 views

What will be the velocity of a comet is falling to the Earth from infinity at the time of impact if Earth had no atmosphere?

What will be the velocity of a comet is falling to the Earth from infinity at the time of impact if Earth had no atmosphere? the comet is falling radially towards the earth. Will this velocity be ...
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0answers
43 views

Determining impact velocity over long distances [duplicate]

Everything I have found concerning impact velocity from a given height deals with constant acceleration due to gravity. I would like to know how to work in varying acceleration into the equation. So, ...
-2
votes
1answer
74 views

Displacement inside the moving Object

Suppose say a person is standing over the moving bike and he jumps while bike is moving, bike will move forward & person will land in same point at which he jumped, relative to earth position ...
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0answers
836 views

Find initial velocity when given max height of 100m [closed]

A ball is thrown straight up. The height of the ball above the ground in (m) is given by the function: $$h(t)=-5t^2 + vt + c$$ What is the initial velocity if you want the ball to reach a max height ...
0
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2answers
209 views

2 bodies separated by a rope [closed]

Say you have two bodies connected by a "weightless" rope, one hanging from a ledge on a pulley (classic pulley problem). If the body that is on the surface and being pulled by the object hanging ...
6
votes
6answers
606 views

How low can an electron go?

Title says it all - recently I encountered a strange homework exercise on de Broglie dual theory with an electron wavelength of few millimeters - which implies the velocity lower than 1 m/s. I ...
-2
votes
1answer
73 views

Given Velocity formula and told to find acceleration, I need help please. [closed]

I tried to do this problem by taking the derivative and it did not get me the right answer. I also tried the Vdv=Ads integration and could not get the right answer. Please Help
1
vote
1answer
143 views

Determine orbital position after change in velocity

I am working on a satellite simulator for a project/game and I am stuck on this one bit of physics. So far I have a satellite that revolves around earth on a 2D plane following Keplerian motion using ...
2
votes
1answer
69 views

Is it possible to affect the trajectory of a black hole?

Basically is the black hole itself affected by the matter going into it? Does it either get pulled by gravity toward things or have its own velocity affected by matter that "impacts" it?
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3answers
202 views

According to relativity, can a statement be true and false in same time?

Say I write following statement on a paper: It's year 2014 at earth. Then I give it to my friend. My friend then starts to leave me and earth to outside with velocity of light. Einstein says the ...
7
votes
3answers
309 views

Does Super Mario physics work in reality? [duplicate]

This illustration summarizes my question: Please assume no air resistance (unless that makes a large difference). Here's what we concluded, but I could use both confirmation and also help with the ...