Questions tagged [velocity]

The time rate of change of the position of an object

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3answers
88 views

What does this equation regarding Kepler's laws of planetary motion actually mean?

I'm doing a project in multivariable analysis regarding Kepler's laws of planetary motions and the following equation was a recommended equality to use, but none of the variables were actually defined:...
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31 views

Why the acceleration is specified if I know the coordinates and velocity?

And I don’t understand why the acceleration can be specified if we know the coordinates and velocity
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62 views

What is the displacement between $t=1$ and $t=8$? [closed]

Given the graph above, what is the displacement between $t=1$ and $t=8$?I thought this was a straight forward questions: It's supposed to be the area under the curve. Moving the time axis up to where ...
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1answer
107 views

how can calculate of terminal velocity in water tank? [closed]

I want to calculate the final velocity of a steel sphere of $10 \text{mm}$ diameter, falling inside a $1\text{m}$ height tank. Also, how to calculate the drag force and the buoyancy force?
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1answer
41 views

Motion along length of a spring [closed]

What's relation between velocity of each part of a massive spring undergoing Simple Harmonic Motion.
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1answer
53 views

Understanding The Average Velocity Equation

From the linear velocity function in Equation 2-11, the average velocity over any time interval (say, from $t=0$ to a later time $t$) is the average of the velocity at the beginning of the interval ($=...
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70 views

Cause of observed galactic red shift or acceleration in expansion of the universe: velocity vs gravity.

Scientist look out at the universe and observe red shifts for galaxies that are roughly proportionate from their distance from us and attribute it to a velocity away from us. Also there is an ...
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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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1answer
76 views

Conservation of angular momentum during rolling with slipping [closed]

A block of mass m moves with a velocity $\mathbf{B}$ on a smooth horizontal surface. It then passes over a cylinder $R$ and mass $m$, capable of rotating about it's own axis through $O$. The block ...
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1answer
77 views

How a particle move with a constant velocity from rest? [closed]

How can a particle move with a constant velocity from rest? I know that the net force on a particle that moves with a constant velocity is zero, so how will it move from rest with a constant velocity ...
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2answers
84 views

Moving a charge with constant velocity

How can we make a positive test charge move with a constant velocity from infinity if the source charge is positive? I know that when a particle moves with a constant velocity velocity the net force ...
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0answers
125 views

Analytical mechanics, constant angle between velocity and acceleration [closed]

A particle moves in a plane so that the angle between velocity and acceleration is constant $\alpha$. Angle $\phi$ between velocity and fixed coordinate axis varies according to a given law: $\phi(t)$....
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806 views

The relation between speed and wavelength

I was taught categorically that the velocity of a wave depends only on the medium in which it travels. Now I just stumbled upon a sentence + formula that declares that "the velocity of sinus-waves ...
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Minimum Time Through Curve

Consider the following conditions: A level road with the path $\vec{r} = \left<x(s),\ y(s)\right>$ A max speed of $v_{max}$ A vehicle with the mass $m$ Tires with a static friction coefficient ...
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If an object moves at constant speed, does it necessarily have constant velocity? [closed]

If an object moves at constant speed, does it necessarily have constant velocity?
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If two bodies move constantly but with different speed, do they move with acceleration relative to each other? [closed]

If two bodies move constantly but with different speed, do they move with acceleration relative to each other?
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3answers
34 views

How is velocity defined in circular motion in central force field?

In my view the velocity is change of displacement in the increasing direction of displacement. Now in circular motion in central force field the particle is changing its direction then how is the ...
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1answer
26 views

Expressing average velocity in terms of acceleration

Average velocity is usually expressed as the displacement divided by the time. For example, $$v_{\text{avg}} = \frac{x(t)-x_0}{t}$$ I have not, however seen it expressed in terms of acceleration. ...
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4answers
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Is there an agreed upon physics definition of the term 'speed'?--for example, can it be negative?

The term speed is commonly defined as follows: https://www.physicsclassroom.com/class/1DKin/Lesson-1/Scalars-and-Vectors Speed, being a scalar quantity, is the rate at which an object covers ...
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Why isn't average speed defined as the magnitude of average velocity?

Speed is usually defined as the magnitude of (instantaneous) velocity. So one could assume that average speed would be defined as the magnitude of average velocity. But instead it is defined as $$s_{...
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3answers
104 views

Kinetic Energy with constant velocity

I am sorry for the question, but I am a noob in Physics. I don't understand why in the kinetic energy's formula the distance is out of the equation. Kinetic Energy formula: $$K = \frac{1}{2}m v^2 = ...
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1answer
102 views

Intuition behind group velocity

Why is the group velocity of the wave given as $\frac {\partial w }{\partial k}$? I understand what the group velocity means but its always given as a definition and I would like to have some ...
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Calculating velocity of a negative charge

From my First Year Physics Textbook: Q1 and Q2 are stationary charges of 7.5x10^-6 Coulomb each. Point P is a mobile charge of -1.6x10^-6 Coulomb, with mass 2x10^-6 kg. Based on a previous part of ...
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1answer
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Which is more efficient in stopping a bullet, small cubes or fine grains of sand

Recently, I was presented with the following problem, relating to pressure: which would be more efficient in stopping a bullet, small cubes or fine grains of sand. Using my intuition, I would say the ...
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2answers
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What is the speed of rotation of the magnetic field of a solenoid or current-carrying WIRE

How does one find the speed of rotation of the magnetic field around a current-carrying wire? or How fast is it circulating around the wire? How does one identify the speed of rotation of the ...
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1answer
209 views

How to calculate the radius of a curve based on vehicle wheel speeds of a car

I have data of the 4 differen wheelspeeds of a vehicle during driving time. Based on that I want to calculate the radius of a curve it is taking. The following are my current thoughts that seem to be ...
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2answers
65 views

Speed of two objects orbiting around a central axis

This question has been bugging me for quite some time and i'm not too sure if i'm missing out some important factor in the understanding of this scenario: Given two objects of equal mass and size ...
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1answer
47 views

For a fluid travelling in a tube, if the pressure is decreased at a constant temperature, how does it affect the velocity and fluid density?

I am interested in understanding the relationship between pressure and velocity, as well as pressure and fluid density. I know that the principle of Bernoulli states that there exists a relationship ...
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1answer
78 views

Which relation is correct for resultant instantaneous velocity in 2d?

Please forgive me if the following question sounds silly and I can't exactly pin point where exactly the problem is but there is some problem with my understanding of vectors. In Cartesian ...
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1answer
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Assistance interpreting equation

Given a position function of a particle: $$ \mathbf r=r\,\hat{\mathbf r}\left(\theta\right), $$ where $\hat{\mathbf r}(θ)$ is the polar unit vector, to find the velocity, we take the derivative which ...
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1answer
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Can acceleration be both the “rate of increase of velocity” and the “rate of increase of speed” in Physics?

A Dictionary of Physics (Oxford University Press) defines acceleration as: The rate of increase of speed or velocity However, from reading many other definitions it seems to me that acceleration ...
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2answers
128 views

What to call an object which is in motion but not accelerating?

I began learning about acceleration and according to the source i learned from an object only accelerates when there is change in vel. &/ direction... what i am wondering is what do you call it ...
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971 views

Can a body be in equilibrium when only one force acts on the body? [duplicate]

I think that when we throw a body in air, at top point the body is in equilibrium but gravitational force is still acting. Is this correct?
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How come group and phase velocity can be different in a non-dispersive media?

I'm a (ex-)physicist working in the applied-physics world and was digging into group vs phase velocities. There is one thing that confuses me : when would that be the case where group and phase ...
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2answers
139 views

Terminal velocity to calculate velocity as a function of time?

Using the equation for drag force, $F = c_d \times \rho \times v^2 \times A \times \frac{1}{2}$, where $c_d$ is coefficient of drag, $\rho$ is air density, $v$ is terminal velocity, and $A$ is ...
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Maxwell-Boltzman speed distribution

For a class assignment, I have to do a Barnes-Hut Galaxy simulation. The assignment includes: The dots' velocities following the Maxwell distribution with typical velocity of $$v={\left<v\right&...
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2answers
236 views

Relativistic equation for motion in a constant acceleration

I found many questions regarding relativistic velocity addition and the relative formula $$V_{x} = \cfrac {V_{x}^{'} + v}{1+\cfrac{vV_{x}^{'}}{c^{2}}}$$ but I found none concerning velocity ...
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1answer
42 views

Distance traveled by accelerating vehicle

Let's say I'm trying to model a train accelerating from speed $v_1$ to speed $v_2$, where the train's mass $m$ and engine power $P$ is known. I would like to find both the time $t$ and the distance $s$...
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Special Relativity Question: Massive particle racing light

I'm a bit rusty on my special relativity and have been thinking about this problem recently: Suppose that a massive projectile (i.e. something large enough that we could see with a telescope) is ...
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1answer
48 views

Velocity and mass and particles

If mass increases as velocity increases how can I associate this with the fact that some particles such as neutrinos which barely have no mass, go faster when they have less mass or less interaction ...
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4answers
363 views

Direction of velocity in curvilinear motion [closed]

My textbook mentions that the direction of net instantaneous velocity is along the tangent to the curve. Well, from the polar coordinate system I also know that the net instantaneous velocity has two ...
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2answers
90 views

Velocity vector for helical motion? [closed]

Problem describes a point particle moving in an upwards helix, with the velocity in the $z$-direction being a constant 3 m/s and circular uniform motion in $xy$-plane along a circle with radius = 6 m ...
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4answers
134 views

Why does the wavelength of a particle go down with higher velocity?

In mechanical waves, the wavelength increases with a higher velocity. λ = v / f. And the wavelength in particles lower with a higher velocity. λ = h / mv.
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How to calculate the position of a fluid parcel knowing the Eulerian velocity

I know the velocity of a fluid, $V(\mathbf x,t)$ for each fixed point $\mathbf x$ and time $t$. From this information, I want to calculate the position in time, $L(t)$, of a fluid parcel that was at ...
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2answers
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Calculating Velocity from Acceleration (Accelerometer)

I am using the Accelerometer in an Android Device to track and detect certain motions, using only one axis as the motions are linear along that axis. I am using a simple filter to remove the noise ...
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1answer
187 views

How to find 4-velocity components in a perturbed metric?

Beginning with a metric with small perturbations \begin{eqnarray} g_{00} &=& 1-2\frac{U}{c^2} + \mathcal{O}(c^{-4}) \\ g_{0i} &=& \mathcal{O}(c^{-3}) \\ g_{ij} &=& -\delta_{ij}\...
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When and how do we use the formula Power = force X velocity?

I'm unable to understand the solution given in this book mine... Why are we adding the resistive force? In fact, i would really appreciate if someone explains the question to me, I'm really struggling ...
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Are mass and velocity complementary

Are mass and velocity complementary? I would like to know if there is a Heisenberg uncertainty relationship between the two. [EDIT] No answers so I thought I would expand a little. The reason I ...
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Using the Kalman filter given acceleration to estimate position and velocity [closed]

I am reading data from an accelerometer. I want to use this data to estimate velocity and position. Originally, I performed a double integration of acceleration to read this data, and as confirmed by ...
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2answers
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Deriving the boundary condition for this flow

The Question: Suppose a circular cylinder of radius $a$ moves with constant velocity $U$ in the $x$-direction in a two-dimensional irrotational, incompressible flow whose velocity decays to zero at ...