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Questions tagged [velocity]

The time rate of change of the position of an object

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Is the X and Y component of initial velocity the same once it leaves the barrel?

So I built this ballista for my physics assignment, it fires at a 45 degree angle. The projectile was in the air for 0.532 seconds and went 3.035 meters. Through this, I calculated that the horizontal ...
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1answer
33 views

Speed of light, can it be not constant? [duplicate]

What if we switch on a flashlight while travelling at the speed of light (we are travelling in vacuum, in a straight path)? What will happen and what will be the speed of light from the flashlight? ...
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2answers
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What part of special relativity is factored in in relativistic redshift velocity equations?

While doing research into redshift equations (doppler redshift and cosmological redshift), both types of redshift had two equations for finding recession velocity: a 'non-relativistic' equation and a '...
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1answer
24 views

How do i get velocity and position from a discrete sample of acceleration? [on hold]

First off I would like to say that I have very little knowledge of physics. This is for a project in Comp Sci where I am requested to make an app that registers a user's phone movement and replicate ...
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4answers
85 views

Is there a concept of velocity at quantum level? [duplicate]

I am confused as according to Heisenberg's uncertainty principle, we cant define the position and momentum of a particle with absolute accuracy simulaneously. Then how can we define velocity at ...
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1answer
76 views

Additive speed of light for three bodies

I know this question, or similar ones have likely been asked before, but I have tried reading several, and they just don't properly explain what I'm trying to understand. The quick version of the ...
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44 views

Yet another kinematics question with non-uniform acceleration [on hold]

A problem is posed where an object is launched into the atmosphere from the surface of the earth at such an initial velocity that it comes back to the surface of the earth after a specific time t. ...
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Motion and velocity [on hold]

A body at rest is given an initial acceleration of 8.0ms for 30 secs after which the acceleration is increased 12.0ms for the next 20 secs the body maintained the speed attained after which it is ...
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Questions on velocity that are multistep? [on hold]

I know these may seem simple but I'd really appreciate how to proceed with these questions. A plane takes off from JFK heading towards Miami, which are 1765km apart. The entire trip takes 5 hours. ...
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3answers
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Can average acceleration be exactly determined from discrete points separated by equal time intervals? [duplicate]

My question: is there an exact expression for the time-average of acceleration in terms of projectile position coordinates measured at instants in time separated by a constant, known time period? I ...
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4answers
3k views

What's the speed of light when viewed from the side? [on hold]

Suppose a pulse of light is sent from $A$ to $B$ in a rigid triangle $ABC$. While the pulse is moving from $A$ to $B$, what is it's velocity relative to $C$? The special character of the photon among ...
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How to solve this velocity and acceleration problem? [closed]

Following is the question I copied from AP Physics class: The answer key for this problem is like this: 1.8 = vt + 0.5*a*t^2 (a = 9.8 m/s^2, t = 2.5s) From this equation, we can solve the speed,...
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Special Relativity collision [closed]

A certain elementary particles lives only a time $T_0\ \rm s$ (proper time) before disintegrating what velocity must the particle have if it is to reach a distance D before disintegrating? Note that ...
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Can some one explain following formula for average impulse of a molecule in the derivation of Boltzmann–Gibbs distribution

Thus, the total average impulse contributed by a molecule with an $x$-component velocity ranging between $v_x$ and $v_x+\mathrm dv_x$, is given by $$2mv_x\cdot\frac{v_x\tau}{L_x}\cdot\sqrt{\frac{\...
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Confusion about 4-velocity

I know that 4-velocity is defined as $$u^\mu = \frac{dx^\mu }{d\tau}$$ $$u_\mu=g{_\mu}{_\nu}u^\nu$$ and $$u_\mu u^\mu=c^2$$ Is it true that $$\frac{d\tau}{dx^\mu} = \frac{u_\mu}{c^2} = \frac{1}{c^...
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1answer
23 views

Forces between wheels and road for a vehicle

Let’s assume we have a front-wheel drive (FWD) car, and we apply a torque (Cf) to the front wheels. At this point, assuming no slip condition, a friction force (Tf) will occur due to friction between ...
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Calculate Escape Speed [closed]

What is the escape speed from a planet that is 4 times the mass of the Earth but has the same radius as the Earth? I have the formula for V-escape as: $$v_{esc}=\sqrt{\dfrac{2GM}{R}}$$ Where $G$ is ...
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2answers
56 views

Definition of velocity in classical mechanics

Let $(r_1,r_2,r_3)$ be the coordinates of a particle $r$ in the coordinate system $\phi$. Let $\{\hat{e_1},\hat{e_2},\hat{e_3}\}$ be the coordinate basis of $\phi$. Why do we define the velocity $v$ ...
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3answers
63 views

Can velocity in $y$-axis be equal with velocity in $x$-axis?

So if $u_y=30 m/s$ and $u_x=30 m/s$ can we say that $u_y=u_x$? my confusion is because velocity is vector they are not equal ( equal in magnitude but not dimension). But can we say that they are ...
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2answers
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Is the direction of average velocity the same as that of average acceleration and that of displacement?

Average velocity is defined as: $\vec{\Delta v} = \frac{\vec{\Delta r}}{\Delta t}$, and average acceleration as $\vec{\Delta a} = \frac{\vec{\Delta v}}{\Delta t}$. It is apparant from these ...
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$v$-$x$ relation, and the ambiguities when solving questions [on hold]

$$v=x^{-1}$$ Find $x$ at $t=2\ \rm s$ if at $t=0$, the particle is at rest. Solution: $$v=x^{-1}$$$$\frac{\mathrm{d}x}{\mathrm{d}t}=\frac{1}{x}$$$$\int^x_0x\mathrm{d}x=\int^2_0\mathrm{d}t$$$$\bigg[\...
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2answers
63 views

How fast would a falling object impact a massive star when released from $10*10^{24}$m away? [closed]

Take the most massive known star, R136a1, with a mass of $5.3 * 10^{32}$kg and a raidus of $2.5*10^{10}$m. Now place a $1$kg metal ball $10*10^{24}$m away (about a billion ly, while still being SI ...
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Instantaneous velocity

So here’s a question I’ve been thinking of for a while. Suppose we say, “an object is having an instantaneous velocity along a particular direction ( say 10 m/s along the $x$-direction)” . Is it fair ...
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1answer
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Angular velocity by velocities of 3 particles of the solid

Velocities of 3 particles of the solid, which don't lie on a single straight line, $V_1, V_2, V_3$ are given (as vector-functions). Radius-vectors $r_1, r_2$ from third particle to first and second ...
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1answer
49 views

Physical meaning of average acceleration

What is the physical meaning of average acceleration? For example, average velocity is that uniform velocity with which if an object is made to move, it will cover the same displacement in a given ...
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1answer
45 views

Kinematics of shooting a projectile at a target [closed]

I want to determine the initial velocity given an angle at which a projectile must be launched in order to hit a target located at a distance $D$ and height $Y$ from the origin. Following the ...
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1answer
67 views

Kinematics Issue w/ negative Velocity [closed]

Given: $$Y = v\sin(\theta)t-\frac 12 gt^2$$ $$D=v\cos(\theta)t$$ Thus: $$\frac{D}{v\cos(\theta)} = t$$ Substituting we get: $$Y=v\sin(\theta)\frac{D}{v\cos(\theta)}-5\left( \frac{D}{v\cos(\...
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2answers
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Calculating the velocity of a proton through Relativity Theory

I was asked to calculate the velocity of a proton through Relativity Theory, with the following information given: -the Total Energy of the proton is 1,500 MeV -the resting mass ($m_0$) of the ...
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Underwater acoustics and the pressure gradient equation

Any input would be very gratefully received, as have now totally overwhelmed myself with calculus, differential integration and indefinite integrals. Aargh! In relation to the 2 equations below: Can ...
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4answers
78 views

Velocity definition in quantum mechanics?

What is the definition of velocity in quantum mechanics? is it an operator?
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1answer
49 views

Calculate Linear Velocity and Angular Velocity After Collision, in SceneKit [closed]

Here is an attached scheme which i want to write my own custom wall reflection method to simulate the ball collision having right (or left, or top/back) spin. As an example, i have created wall node ...
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2answers
67 views

Velocity of separation and velocity of approach [closed]

Can I have a clear cut dimension or difference between velocity of approach and velocity of separation? In just simple 1D motion. Considering two rigid spherical masses of different masses and ...
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3answers
59 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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3answers
30 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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2answers
57 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
30 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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Velocity of two points with different reference frames on a rigid body

I have a question which comes from a practical application I am currently working on. I have a car with a sensor attached to its right rear corner, which is supposed to provide us with car's speed ...
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1answer
35 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
45 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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1answer
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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
59 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
36 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
62 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
101 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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2answers
71 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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0answers
23 views

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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2answers
136 views

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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1answer
49 views

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
32 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 ...