Questions tagged [velocity]
The time rate of change of the position of an object
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Calculating how fast an object would go with a certain mass and energy
Say you have an object with mass M and energy E, how fast would it go? I know that you could just use the formula for kinetic energy E=(MV^2)/2 and then solve for V (V=sqrt(2E/M)), but that’s only an ...
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Where does "excess" energy go when a vehicle uses a lower gear to move at a given speed?
So I understand that a lower gear as advantageous when accelerating a vehicle or when driving up hill (e.g because you are having to accelerate against gravity). I know this is because of the ...
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Is it possible to have a uniform speed but variable velocity in one-dimension motion?
Is it possible to have a uniform speed but variable velocity in one-dimension motion? I saw a lecture where teacher said that it is possible if particle changes its direction of motion 180$^\circ$.
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Density of states - as a function of electron velocity
A condensed matter textbook states that in a 3D gas of electrons obeying the Fermi-Dirac statistics the number of electrons per unit volume having velocity components in the ranges $u, u+d u$, $v, v+d ...
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Why acceleration is not always parallel to velocity but velocity is always parallel to displacement? [closed]
Velocity is derivative of displacement :
$$\vec v=\frac{\mathrm {d\vec r}}{\mathrm dt}$$
And acceleration is derivative of velocity.
$$\vec a=\frac{\mathrm {d\vec v}}{\mathrm dt}$$
Given that their ...
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Why is velocity used for kinetic energy instead of speed? [duplicate]
This may seem like a self-explanatory question, but if kinetic energy is a scalar quantity, and squaring the velocity essentially removes its vector quality, why not use speed instead?
I have a hunch ...
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How 'fundamental' is position?
From my knowledge, which is admittedly inadequate, it seems that in Classical Mechanics and other parts of physics, the integral of position isn't used at all. As in, one can easily imagine scenarios ...
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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 ...
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Bose-Einstein statistics: What would the average or expectation value of velocity $\langle v \rangle$ be for an ideal Bose gas?
I would appreciate if anyone could provide me with the general velocity distribution probability density function and compare the same with the Maxwell-Boltzmann velocity distribution.
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Velocity of a body after rising out of a ideal liquid
Suppose you have a cube of volume $S m^3$ and you submerge the lower edge of the cube to a height $h$ below the surface of the liquid. $h>S$ i.e the cube is completely submerged.
Now, once you ...
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Why mean time between collisions has two formulas one with drift velocity and one with average speed?
Drift velocity is defined as :
$$V_{dx}=\frac{e \tau}{m_e} E_x$$
Therefore, mean time between collisions is τ= $\frac{m*v(drift)}{eE} $
however, τ is also τ=$\frac{\Lambda}{<v>} $ in which $<...
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In the formula for the conservation of mechanical energy, what does mean the velocity?
For example I have the formula:
MEI=MEF
mgh+mvi2/(2)=mgh+mvf2/(2),
What does initial and final velocity mean?
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How to calculate the final position of a particle under variable accelaration and its instantenous velocity?
I'm a first-semester physics student who was recently on a train. On a screen, it said the instantaneous velocity of the train was 176 km / h. We had 4 min left until our destination. I wanted to ...
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Changing variables from $\dot{q}$ to $p$ in Lagrangian instead of Legendre Transformation
This question is motivated by a perceived incompleteness in the responses to this question, which asks why we can't just substitute $\dot{q}(p)$ into $L(q,\dot{q})$ to convert it to $L(q,p)$, which ...
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Circle to Polygon & Circle to Circle Velocity Resolution
I current am working a 2d physics engine, but have recently hit some bumps in the road.
Polygon to polygon collision and velocity resolution works without issue, but I am struggling to get working ...
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Statistical independence of $x,y,z$ dimensions for Maxwell velocity distribution function
I have been looking into the derivation of the Maxwell speed distribution function as for instance given in https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution#...
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In this conservation of momentum problem, where is the sign error coming from?
Say I have a particle travelling in the $x$-direction and breaking into two pieces:
Conservation of momentum in the $x$-direction obviously gives:
$$mv = m_1 v_1 \cos(30) + m_2 v_2 \cos(60).\tag{1}$$
...
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In $a = dv/dt$, is $a$ the net acceleration? [closed]
While going through the calculus approach to accelerate, we have,
$$a = dv/dt, $$
I think, here, v and a should be in the same axis,
is my process correct?
in a planar motion in two dimensions, it ...
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How does the distribution of floor choices of your co-passengers affect your time of arrival in an elevator?
Note: This is a wiki post.
Suppose you are late for a meeting and you have to take an elevator. The floor choice of your fellow passengers influences how late you will reach your destination. If ...
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Average velocity showing different results
I was solving a question, in which, a particle has travelled a distance $s$, with initial velocity $0$ and constant acceleration.
So the equation of motion becomes,
$$ v = a t \tag{1} $$
and
$$ v = \...
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How does a seatbelt help in a car crash? [closed]
If you are in a car crash, you will likely have on a seatbelt because they are supposed to help you from getting injured/harmed. But, I don't think they are that much of a help. First of all, say you ...
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Determining star position and velocity to deduce closest approach?
I am trying to replicate the results found for Gliese 710's closest approach of ~0.05 parsecs in 1.3 million years approximately. I thought that by plotting the sun at (0,0) and using the stars ra,dec,...
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Magnitude of Acceleration Vector when Speed is Constant
If I observe a change in direction of velocity, but not in speed: What does the acceleration vector look like?
I am confused! The difference vector between two vectors of equal length A has a ...
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Why isn't the tangential velocity of circular motion zero?
Why is tangential velocity 2πr/T if the body's total displacement in the end of one revolution is zero?
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Instantaneous speed x instantaneous velocity
Related to Distinguish between instantaneous speed and instantaneous velocity
I understand that the average velocity is given by the displacement divided by the change in time, and it is a vector ...
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Confusion regarding Special Relativity and Relativity of Velocity? [duplicate]
Suppose that there are two points in an empty space A and B and observers at A and B having clocks:
If A were to be traveling near speed of light, when clock at A passes 1 hour, observer at A ...
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About Constrained Speeds
My question is whether there is any known method, which doesn't use calculus, to find the speed of ball C, given that the speeds of balls A and B are given at a certain moment in time. Suppose that in ...
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How do I calculate frictional forces of an object sliding laterally on a sloped plane?
Game developer here. Most problems about objects sliding down sloped planes with friction are about the object sliding in the natural downward sliding direction of the slope. But how would you ...
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Track an object velocity in a 2D plane
I would like to track the motion (actually, I am more interested in the velocity) of an object in a 2D plane (typically 4m x 4m). The object speed is typically 10cm/s, but the mouvement may be chaotic ...
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Does acceleration or deceleration affect the strength of impact if velocity is the same?
2 identical cars both hit a wall at the same exact speed (let's say 50 mph), but one car was speeding up to 50 mph and the other car was slowing down to 50 mph. Also let's assume that the cars are ...
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Faster than light is possible? [duplicate]
I know that some particles can go near or more than half the speed of light. So, say we shoot two particles in opposite directions at more than half the speed of light. Say one is moving at 50% the ...
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If a force depends on velocity, then why is the force not conservative? I need a formal proof [duplicate]
I am currently an undergraduate taking a course on Newtonian mechanics. The lecturer defines a force to be conservative if there exists a scalar function (we call it potential function), say $V(x,y,z)$...
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Why does my 3rd method not show me that power = force dotted with velocity?
I have derived 3 expressions for the power that a force, $\vec{F}$, transfers to a body. (A) and (B) are consistent, but (C) isn't. Where have I gone wrong with (C)? EDIT: THE MISTAKE HAS NOW BEEN ...
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How to Calculate frequencies, $C$ and Group $Cg$ from a dispersion relation?
Some people requested what was the context of the question and this is where it comes from:
"Given the dispersion relation: $w^2=w_0^2+A^2k^2$ ( $w_0$ and $A$ are constants)
Which frequencies ...
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If falling coconut has more momentum than a bullet then why bullet is more deadly? [closed]
Imagine a coconut of mass 1kg is falling from a 10m tall tree, the momentum is around 14kg.m/s (I don't know how to format my work but just trust me)
and then the momentum of a bullet of mass 0.01kg ...
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Paradoxical result arising regarding velocity
I was working on a problem that goes like this
Bob beats Judy by 10 m in a 100-m dash. Bob, claiming to give Judy an
equal chance, agrees to race her again but to start from 10 m behind the
starting ...
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Why is it that objects inside a moving train tend to move at the same speed as the train itself?
I mean I get people saying because it's Newtonian mechanics. Everything inside the train will have same speed as that of train but my question is why ? Why is it like that ? And How does that happen ?
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What's the fastest speed water from a glacial dam burst could achieve? [duplicate]
I've been watching a lot of Graham Hancock videos of late, thrusting myself deep into the rabbit hole of pseudoarchaeology/alternative archaeology, and I don't really know enough to assess the ...
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What does instantaneous velocity mean? [duplicate]
What does instantaneous velocity mean?
on google it says "Instantaneous means something happens very quickly, in a single moment. It's similar to the meaning of "instant", but most ...
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Critical velocity of a fluid
Critical velocity($v$) of a fluid is given by
$v = \frac{Rr}{\rho\eta}$
where,
$R \rightarrow$ Reynolds number
$r \rightarrow$ Radius of tube
$\rho \rightarrow$ Density of fluid
$\eta \rightarrow$ ...
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How can position of charge moving under magnetic field have different positions for different observers
Assume we have a point charge $Q$ moving with velocity $\vec{v}$ with respect to an observer at rest and is in the presence of magnetic field $\vec{B}$. $\vec{B}$ and $\vec{v}$ are perpendicular to ...
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Given a distance, and velocity as a function of time, how do I find the time taken to travel the distance? [closed]
Given the velocity of a particle as a function of time V(t), and a distance between two points on a straight line (from point A to point B), I would like to find the time it will take the particle to ...
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How is velocity defined for different systems?
I'm currently a beginner learning classical mechanics, and I just learned about the Lagrangian formalism. I completely understand the theory behind it, but a lot of times, I'm not able to calculate ...
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Understanding velocity as a vector quantity [closed]
Why is velocity classified as a vector quantity. Can it be explained by the same way as force referring to the Phys.SE post Where am I confused about force addition?
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How to find rest mass?
I have two identical massess with rest mass $m_0$. One of them is made to move with very high velocity $v$, while other is at rest. At some point in time the moving mass collides with the stationary ...
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What is the error in the following way of finding phase difference between two sound waves? [closed]
Consider the 2 incoherent sound waves,
$$S_1 = S_0\sin{(\omega_1 t-k_1 x)}$$
$$S_2 = S_0\sin{(\omega_2 t-k_2 x)}$$
Phase difference:
$$\Delta\phi = \omega_1 t-k_1 x -\omega_2 t+k_2 x$$
Using $kv=\...
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Stationary Obversers in Brinkmann Coordinates
The four-velocity of a stationary observer is defined as $U^{u}$ = $\left (\dot{t},0,0,0 \right )$, where t is the time coordinate in some four-dimensional coordinate system, and overdot represents ...
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Formula for adding velocities in opposed motion at relativistic speeds from the perspective of a stationary observer
I'm confused by the formula 𝑢=(𝑣+𝑣′)/(1+𝑣𝑣′/𝑐^2) whenever I apply it to a specific thought experiment.
I have a third party, stationary observer, who observers to collinear objects moving ...
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Drone in an elevator
I just watched this video, What Happens If You Fly a Drone In An Elevator? Real Experiment!
To my surprise, the answer was not what I expected. I thought the drone would stay stationary. My thought ...
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Coriolis force relation to wind velocity
I'm learning coriolis effect on Winds moving from equator towards North pole. This is for geography.
Question:
Why is coriolis force stronger for winds having larger speed(larger component of ...
