Questions tagged [velocity]
The time rate of change of the position of an object
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FInal velocity of object on an inclined plane given angle, time, initial velocity [closed]
A sled starts from rest, and slides down at 38.0 degrees frictionless hill for 4.24 s. How fast is it going at the end in m/s? How did you solve it? Thanks!
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Velocity Time graph [closed]
I'm trying to help someone with their A level maths and I'm perplexed by this question.
A car starts from rest at time $t=0\,\rm s$. It accelerates uniformly until its speed reaches $V\, \rm{m/s}$.
...
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Problem in deriving the four-momentum with lagrangian
Now, the Lagrangian is
$$L = -m \sqrt{-n_{ab} \frac{d\xi^{a}}{d\lambda} \frac{d\xi^{b}}{d \lambda}}.$$
In the notes i am reading, it was said that the momentum $$p_{a} = \frac{\partial L}{\partial (\...
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1answer
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Plot velocity and acceleration in Matlab\Octave knowing that $v(t)=\frac{t}{t^2+1}$
An object of mass $m$ is observed moving along a straight line parallel to the $Ox$ axis. The scalar component of the object's velocity is given as a function of time by $\frac{t}{(t^2+1)}$, where t ...
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1answer
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How to calculate constant acceleration required to move an object by a distance $d$ in time $t$?
I’m working on an animation software and I require objects to have a downward acceleration. They currently fall at a constant velocity but I want to make them accelerate to make the animation look ...
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Need Help with Physics Problem! [closed]
I got this problem while practicing and I need help with it!
A fighter, traveling at 443 m/s fires a bullet at an angle 12◦ from the perpendicular toward the front of the plane. The muzzle velocity ...
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Need help getting out of speeding ticket via physics. SOS [closed]
I'm a college student and I received a ticket going 94mph in a 70mph zone in CA. I genuinely do not believe I was going that fast. I was planning on refuting the ticket via written declaration and ...
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1answer
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Position of a charged particle in a radial electric field
I am trying to work out the radial position of a charged particle in an attractive radial electric field due to a fixed point charge.
The acceleration of the particle is C/(r^2) where C is a const and ...
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Does velocity always vanish at the trailing edge of an aerofoil?
In our fluids notes we derived the velocity field around a *symmetrical *Joukowski aerofoil by using a complex potential, and showed that, with the Kutta condition applied, the velocity at the ...
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2answers
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Not understanding velocity addition (or substraction maybe) in special relativity
Suppose there is a train that has a velocity of $v=0.6c$. It travels $L_0$ distance in $T_0$ time. They are measured by a person sitting on a bench beside the track. So from train's perspective ...
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What is the exit velocity of a charged mass travelling parallel to field lines in an electric field (between two plates)? [closed]
I did some pretty basic calculations and I got the exit velocity as $sqrt(2qUm)/m$ where $q$ is the charge, $U$ is the voltage across the plates, and $m$ is the mass.
The reason I'm sceptical is ...
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Why are velocity dependent forces considered non-central?
I was going through Classical Dynamics of Particles and Systems (Thornton-Marion, 5ed). On page 50 it is stated:
Any force that depends on the velocities of the interacting bodies is considered non-...
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1answer
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Distance calculation without knowing time [closed]
I’m studying physics and am struggling to work out the correct formula for the below example question. Any help and explanation would be amazing.
A tourist being chased by a bear is running in a ...
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How to solve the following exercise? [closed]
On the slope with a height of $2.0 m$ and the horizontal side of the slope of $5.0 m$, a sled descends, they accelerate evenly to the foot of the slope.
Calculate the acceleration and final velocity ...
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1answer
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What's the speed of the train with our point of reference being the person who's moving inside the train? [closed]
A person moving in a train with the speed of 1m/s to the right, while the train is moving in the same direction with the speed of 10m/s
From the person's point of view "considering that the ...
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1answer
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Proof in the theory of relativity [closed]
If the speed of a particle is smaller than the light
speed in one inertial frame of reference then it is smaller than the light speed in any other inertial
frame.
This is a question our lecturer has ...
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Acceleration is given in terms of position then it has been asked to find the position at time t
The question is as follows :
The acceleration $a$ of a particle is given as $a(x) = x$ where $x$ is the position of the object on the $x$-axis. Then find the position of the object in terms of time $...
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3answers
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Average velocity derivation [closed]
Most of the time we make a mistake when calculating average velocity where
$$\bar v'=\frac {\sum v} n$$ but the actual is $\bar v=\frac {\sum s} {\sum t}$, can we use the wrong to get the correct ones?...
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1answer
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Elegant way to find maximum range of a projectile launched from a height
A projectile is launched from a height of $h$ and the initial velocity
of $\sqrt{2ga}$. Find the maximum range achieved by the projectile in terms of $g$,$a$, and $h$.
I can go about the traditional ...
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2answers
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Is there a way to solve the following differential equation for a sphere rising in a fluid?
Given the boundary conditions, how do I find the analytical solution (for the velocity) of the following expression:
$$ \left(\frac{2}{3} \pi \rho_f a^3 + \frac{4}{3} \pi \rho_s a^3\right) \frac{d ^2 ...
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2answers
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Estimation of greatest speed in a polyhedron
in order to control velocities in a three dimensional volume, I look for a proof or a proof idea for the following assumption:
Given a non-empty solid polyhedron in 3D, all points inside this set ...
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Is this intuition correct? (dot product)
So, it is based on the article below: Go to the bottom of the article where the 'Mario-Kart Speed Boost' example is.
So, the intuition in the examples makes sense to me but sometimes people explain ...
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1answer
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Is there a word to describe when things are moving individually, but have a net velocity of zero?
I know this is a strange question, but I know there must be a word for it.
So imagine a case where, taken as a whole, the net velocity of all particles equals zero, but each individual particle is ...
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1answer
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How is speed of Milky Way determined relative to CMB dipole?
I read that our galaxy the milky way is moving at approx 630km/s relative to CMB dipole, I think they applied Doppler shift to find this number but how do they do that? I know when universe is a hot ...
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1answer
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Physical meaning of the real part of the conductivity as a function of frequency for a time-dependent electric field
I apologize if this question has been asked before. My Solid State professor was explaining the Drude model, and what happens to a solid when we apply a time-dependent electric field. In a lecture, we ...
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1answer
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Is the relation “slope=velocity” mathematically valid?
$\text{Slope= tan(angle with respect to positive X-axis)= scalar output}$
$\text{velocity= a vector }$
Source: Hugh D Young_ Roger A Freedman - University Physics with Modern Physics In SI Units (...
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4answers
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What is the difference between m/s and m/s/s?
Can I subtract, say, for example, 600 m/s - 20 m/s/s? I am confused about this topic and there is no good information on the web.
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1answer
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Is there a difference between instantaneous speed and the magnitude of instantaneous velocity?
Consider a particle that moves around the coordinate grid. After $t$ seconds, it has the position
$$
S(t)=(\cos t, \sin t) \quad 0 \leq t \leq \pi/2 \, .
$$
The particle traces a quarter arc of ...
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2answers
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Electric current and motion of electrons
When a battery provides energy to an electric circuit, the electrons get aligned so as to transfer energy from the negative terminal to the positive terminal. The drift velocity of the electrons in a ...
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1answer
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A 1 meter radius ring spins around its axis at 10 revolutions per second. It is now dropped to the ground [closed]
A 1-meter radius ring spins around its axis at 10 revolutions per second. It is now dropped to the ground, where it rolls steadily in a straight line. Assuming it does not lose any energy to friction, ...
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Is velocity real?
This sounds like a stupid question but I am do not grasp physics concepts easily. "Velocity" is just the change in displacement over the change in time. I can see displacement and time as ...
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2answers
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Need some help understanding velocity
I have just started learning kinematics and this is just a small question, that I wish for to clarified as it feels a little bit confusing. Below, the difference between speed and velocity is given. I ...
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1answer
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What is the meaning of word 'rate' in physics?
Often, I have seen in physics the rate of change of velocity or something like that in kinematics. And in question based on speed, time and distance. I would like to know the meaning of the word rate ...
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1answer
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Who observes the light faster when the lamp is also traveling?
Say I have a lamp on a car $M$ in the middle of $A$ and $B$, who are both $c$ distance away from $C$. (so it takes light 1 second to travel to both $A$ or $B$ from $M$). Now the car starts traveling ...
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4answers
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If displacement is 0, does that mean initial velocity equals final velocity?
For instance, one of the kinematic equations is :
$$v_f^2 = v_i^2 + 2ad$$
where $v_f$ is final velocity, $v_i$ is initial velocity, $a$ is acceleration, and $d$ is displacement.
Say for instance a guy ...
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1answer
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Find the pointing of maximum velocity on a trajectory
I understand the fact that we need to calculate the derivative of velocity with respect to time and equate it to 0 to find when $v$ is at max. In the following part of the solution, $v(t)$ has already ...
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1answer
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Identifying variable in an ion thruster problem
recently came across a school revision problem introduced my teacher about ion thrusters. With the assumption that we are ionising air (Nitrogen) and that the ions accelerate by mutual repulsion ...
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Group Velocity Clarification
There is something that confuses me a bit about how group velocity is sometimes introduced and explained. For example, Walter Lewin (great professor) in his lectures uploaded on youtube, explains the ...
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1answer
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Why is speed measured along the line of sight (LOS) a factor $\sqrt{3} $ smaller for randomly distributed velocities?
I encountered this problem from Introduction to Modern Cosmology by Andrew Liddle.
I had the exact same doubt as the OP of that question had, and the first answer makes sense but I don't understand ...
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1answer
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Pressure and velocity in fluid dynamcis
I want to ask whether someone could help me solving a problem in understanding the relationship between pressure and velocity in fluid dynamics, please?
Why do I know that particles are not by ...
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2answers
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Problem in instantaneous acceleration and instantaneous velocity
Recently i came accross a problem that said
An object is dropped straight down from helicopter the object falls faster and faster but its acceleration decreases over time becoz of air resistance. the ...
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1answer
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What is the direction and orientation of a pendulum's acceleration at the ends of the oscillation? And at the midpoint? [closed]
A simple pendulum (a body oscillating at the end of a wire) describes an arc of a circle at each oscillation.
What is the direction and orientation of the body's acceleration at the ends of the ...
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1answer
37 views
Time derivative with respect to an observer moving with velocity $\mathbf{v}$
I am taking a class in fluid mechanics right now and my book has this statement with no explanation:
What is the time derivate seen by an observer moving with a velocity $\mathbf{v}$ of a scalar ...
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Query regarding instantaneous velocity and instantaneous acceleration
Suppose an object's velocity is $5 \ \text{m/s}$ at $t = 1$ seconds and $8 \ \text{m/sec}$ at $t = 2$ seconds then the acceleration here is $3 \ \text{m/sec$^2$}$ i.e at $t = 1$ seconds the ...
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1answer
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Does relative work done affect temperature of a body? [duplicate]
Imagine a bus travelling at a speed of 20m/s towards the positive x-axis with respect to ground frame. That bus is quite long(just for a safer Side) and two persons 'A'and 'B' located inside that bus ...
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1answer
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What does graph of a function mean?
I'm asked to do a graph for the speed of the rocket as a function of the flight altitude.
Here are the values: h (m) 0 4 13 32 55 83 103 and v (m/s) 0 4 7 12 16 20 23. Does this mean that the flight ...
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3answers
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What is the difference between two types of velocity?
What is the difference between $v=\frac{s}{\Delta t}$ and $\bar{v} =\frac{\Delta\bar{x}}{\Delta t}$, are they the same?
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4answers
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Can we explain velocity without time? [closed]
I'm trying to wrap my head around inertia/velocity, or just change in general, I guess. I'm unsure exactly sure were my gap is, or what question to ask, so I'll explain with a scenario.
Lets say I'm ...
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2answers
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Do non-inertial effects impact velocity, or just acceleration?
Suppose you measure motion in a non-inertial frame and get fictitious acceleration terms from centrifugal and Coriolis forces. Will these terms produce fictitious velocity terms?
Dumb question, and I ...
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Special relativity: Two moving objects from different reference frames [duplicate]
Imagine a inertial frame of reference, in which two objects are moving with constant velocity in opposite directions. Object one is moving at $50$% the speed of light and object two has a velocity of $...
