Questions tagged [velocity]
The time rate of change of the position of an object
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A car travels along the circular path, what's velocity and acceleration? [closed]
I'm trying to solve this question for few days but couldn't get into any answers. it would be great if anyone could give me a little help for this.
The car travels along the circular path such that ...
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2answers
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In the equation: $a = dv/dt$ , is $dt$ the time taken to achieve that instantaneous acceleration?
If you solve for $dt$ from $a = \frac{dv}{dt}$ , is it the time taken to to achieved that instantaneous acceleration?
$a$ : acceleration
$v$ : velocity
$t$ : time
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Dynamic Bend Angle During Explosion Bonding Process (Simple Vector Problem)
For some reason this makes no sense to me. The setup is pictured: A flyer plate at a fixed distance from a base plate has explosive placed on top and is accelerated into the base. $V_D$ and $V_C$ are ...
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How do I calculate the velocity or speed of a ball coming off a paddle wheel? [closed]
I'm trying to calculate the speed at which these "marbles" would be traveling once they reach the end of the vanes in the wheel. I then would like to calculate the energy at which they impact a fixed ...
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3answers
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What does the first derivative of (2-norm) distance with respect to time tell us?
My basic physics' knowledge is a little rusty. My apologies in advance. I know that the first derivative of position or displacement with respect to time is the instantaneous velocity. Suppose I have ...
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What is the terminal velocity of a carpenter's axe in sea water? [closed]
In the bible, the giant mythical bird called the Ziz stood in the ocean, which was only deep enough to cover its feet. In the same spot where the bird stood, a carpenter's axe supposedly fell and took ...
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If an object is pure rolling how does the object move or rotate if its point of contact has zero velocity?
If its point of contact is at rest then how does an object even rotate without tangential velocity,i don't also see how the object moves if one point of it is at rest and the other points are moving,...
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The relation between rebound angle and angular frequency of dropped spinning ball?
The dropped ball is spinning around a horizontal axis and bounces away from the vertical at an angle. I tried solving this problem using the angular and linear momentums with the following logic: ...
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3answers
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Why don't these conversions of time between reference frames seem consistent? [closed]
I am a student and due to school closures I am reading ahead in physics. I have been learning about relativity and I made up a problem for myself. You can see a diagram that I drew below:
The diagram ...
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1answer
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Velocity of particle due to acceleration. Special relativity
I understand how to do transformations of four velocities, acceleration and so on under Lorentz boosts. However after all I have learned in special relativity I still don't know how just an ordinary ...
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1answer
31 views
When the rate of acceleration changes it's sign how does the velocity change?
When the rate of acceleration changes its sign how does the velocity change? When another derivative of distance with respect to time is increased how does it affect factors like displacement and ...
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2answers
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Constant or Uniform Velocity and acceleration
I get confused understanding Constant or uniform Velocity and acceleration when I understand constant speed which means that same distance traveled at same time.
So constant or uniform velocity ...
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3answers
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Special Relativity - Reference Frames S and Sā² relative velocity [duplicate]
Consider the standard arrangement in special relativity. Let $S'$ move in the positive $x$-axis with a velocity $V$ with respect to $S$
Question: $S$ then moves with a velocity $-V$ with respect to S'...
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2answers
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Do Lorentz transforms use velocity or speed?
Suppose we have the $S'$ frame moving at some velocity $v$ in the $X$ direction relative to the $S$ frame, then it follows
$$x' =\gamma (x+vt), t'=\gamma(t+\frac{vx}{c})$$
From my understanding, to ...
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2answers
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What if the directions of the initial and final velocity are different in the conservation of mechanical energy equation?
I saw a problem, and saw that it could be easily solved using conservation of mechanical energy. So I wrote my equation:
$$mgh_1 + \frac12mu^2 = mgh_2 + \frac12mv^2$$
Where $u$ is initial velocity, $...
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2answers
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If I'm moving at half the speed of light $c/2$, and another object with $c/2$ in the opposite direction, will I move with speed of light? [duplicate]
... c/2-(-c/2)=c relative to the other object? (title character limit)
Alternatively
If my speed is c/n to the object behind me, which also has c/n to the one behind it and so on I should have a ...
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4answers
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How can there be acceleration but no velocity at instant of maximum height when object projected upwards? [duplicate]
When we project an object vertically upwards its velocity at maximum height consider to be zero but still, it has acceleration due to gravity i.e $9.8\mathrm{m/s^2}$. But mathematically we know that ...
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3answers
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Why do two 'transverse waves' travelling in same medium have the same wave speed?
Why is it that two transverse waves travelling in same medium have same wave speed? What does the medium has to do with it? I have searched through the web, but I couldn't understand. I have found ...
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5answers
555 views
Can an accelerating body be at rest?
A block of mass $1~\rm kg$ is lying on a table. It is stationary because the gravitational force is balanced by the force from the table. But the body should have an acceleration $g$ and consequently ...
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4answers
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Can I find the acceleration or velocity when my displacement-time graph is discontinuous?
Today, I encountered the problem where I was asked to find the velocity and acceleration from displacement-time graph but the displacement-time graph was discontinuous. So I am unable to find the ...
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Direction of motion in rolling without slipping [closed]
Suppose a disc wrapped with wire is given a forward linear velocity and rotated anticlockwise.will the disc go forward or backward.similarly when rotated clockwise with forward linear velocity,what ...
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1answer
34 views
Forces: Initial (momentarily or short) push and initial velocity [closed]
A body is resting on a horizontal surface with friction (both static and kinetic friction are counted). Then it (the body) was given a momentarily (short) push greater than the maximum static friction ...
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2answers
31 views
Linear momentum conserved on a boat? [closed]
A man of mass $m$ is standing at one end of a stationary, floating barge of mass $3m$. He then walks to the other end of the barge, a distance of $L$ meters. Ignore any frictional effects between the ...
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4answers
611 views
If velocity in forward and backward directions is positive and negative respectively, then what is it in left and right directions? [closed]
I have defined velocity in forward direction to be positive and negative in the backward direction. So what is the velocity if the body is moving right or left?
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1answer
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Recoil velocity of atom after photon absorption
I'm trying to calculate the recoil velocity of a stationary atom after absorbing a photon, in terms of $E$ and $m$.
I've tried manipulating relativistic equations, keeping in mind conservation of ...
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1answer
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What does a function of proper time mean and how do you transform from proper time to real time?
A covariant formulation of electromagnetism says the equation of motion of a charged particle in an electromagnetic field is $$m\frac{du_\mu}{d\tau} = qF_{\mu\nu}u^\nu.$$
But this equation is in terms ...
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2answers
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Can We Explain Length Contraction in a Simpler Way?
I have been studying relativity from a decent amount of time and all the books have a common thing.That is, They explain time dilation in a simple independent way but for length contraction they ...
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13answers
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Why don't we use rapidity instead of velocity? [closed]
In school we learn that we can add velocities together, and then later on we learn that it's not correct and that there is a speed limit. Why create all this confusion when we could just use rapidity ...
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Thermal velocity/agitation--why don't we feel 'hit' by ambient gases?
If I'm not mistaken, the molecules in gas move at insane speeds at room temperature (for some gases, ~1 km/s) due to thermal agitation. Why don't we feel 'hit' by this random motion?
https://www....
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Mass is affecting final velocity down ramp
I have been doing an experiment where 2 different skateboard frames (like a grind) slide down a metal ramp (1.5m) and the final velocity is calculated by video analysis. I would compare this to the ...
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1answer
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Conversion of cartesian position and velocity to spherical velocity
Let's say that there is a particle with Cartesian coordinates $(x,y,z)=(1, 2, 3)$ and Cartesian velocity $(x', y', z')=(4, 5, 6)$.
Converting the position to spherical coordinates is straightforward:
...
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Maxwell velocity distrubution: why is it effectively dependant on magnitude?
I'm trying to understand how Maxwell velocity distribution is derived.
I'm using Chapter 2 of this PDF as a base.
I'm trying to understand this part:
With the definition of the probability ...
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4answers
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Can we calculate centripetal acceleration by using this method $\frac{\mathbf v_2-\mathbf v_1}{T}$?
If we know the angle between two velocity vectors $\mathbf v_1$ and $\mathbf v_2$, and if we know the time $T$ it takes for the velocity to change from $\mathbf v_1$ to $\mathbf v_2$,then is it ...
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2answers
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Can we assume a force to already be negative before knowing the value of it? [closed]
Let me make my question clear by the following example:-
Letās take a case of an individual who is in an elevator accelerating downward with some acceleration ā a ā such that āaā < g . Letās take ...
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What is the formula for finding the maximum speed a 1kg mass would reach going towards a larger Mass $M$ starting at a relative speed of zero? [duplicate]
If all that exists in the universe were two masses (one with mass 1kg and the other with mass $M$) what is the formula for the maximum speed they would have relative to each other right before impact? ...
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1answer
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D'Alembert's principle derivation in Goldstein's Classical Mechanics book [duplicate]
(I could not find any answer to the following question in other related questions posted on SE, so asking it here.)
In the derivation of D'Alembert's principle in his "book", Goldstein uses the ...
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1answer
51 views
Direction of force in special relativity
If a spring is compressed, you can release either end and it will expand outward at the same speed irregardless of which end is released (just in opposite directions). However, if the spring is moving ...
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2answers
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Is acceleration of electron and speed of electron in a wire inversely related?
So we know that $${\vec{E}}= \rho{\vec{{J}}}$$ (where ${\vec{J}}$ is current density, and $\rho$ is resistivity).
and then, $${\vec{F}}= q{\vec{E}}$$ and $$q{\vec{E}}= m{\vec{a}}$$ so we can write ${\...
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1answer
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Time component of the four-velocity and the speed of light
If we write the four velocity of an object we have,
$\vec{u} = (c\gamma_u, \gamma_uu^x, \gamma_uu^y, \gamma_uu^z)$
Since $\gamma_u > 1$, we see that the $u^0 > c$, and it seemed so strange to ...
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1answer
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How to determine where an object will land on a variable elevation surface?
I'm making a game and I need to figure out the exact point on a hilly surface where the car will land after the jump.
Here is an image:
So since this is a game, it's very easy for me to figure out ...
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5answers
327 views
Problems regarding components of velocity
I find it extremely difficult to resolve velocities into components to solve certain problems . A few examples are the following :-
Point $F$ is pulled down with velocity $u$ . Point $D$ is ...
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3answers
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Can you use $a=$$\frac{\Delta v}{\Delta t}$ instead of $\frac{dv}{dt}$ to find instantaneous acceleration?
Can you use $\frac{\Delta v}{\Delta t}$ instead of $\frac{dv}{dt}$ to find instantaneous acceleration?
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Silly question about calculation of $4$-velocity vector
I would like to know if it is possible to state (choose) always that:
$$ u_{\mu} = (-1,0,0,0) \tag{1}.$$
Then, knowing $(1)$ you can raise the index,
$$u^{\mu} = g^{\mu\nu}u_{\nu}, \tag{2}$$
and ...
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1answer
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Doubt on how to calculate 4-velocity components
I know that already exist a question on How to get the four-velocity components from a given metric tensor?; the conclusion of the answers were that 4-velocity and the metric are quite unrelated ...
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1answer
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Definition of velocity in the context of affine space
In many texts you see the definition of velocity as the time derivative of position. In the context of affine space, position is not a vector quantity. So in the context of affine space, is the ...
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2answers
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Constant angular velocity in vertical circular motion?
I want to do the following vertical circular motion experiment, where I "hand spin" a rotating mass (red) that is attached to the same string with the slotted mass at the other end. I spin the mass by ...
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1answer
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Doubt regarding electric current [duplicate]
If we consider a simple dc circuit with just a resistor, we notice that V is constant and so is the length through which current is flowing, hence the electric field is constant. So why does drift ...
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1answer
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Problem regarding relative velocity [closed]
Train A moves north with speed 54km/h. What is the velocity of a monkey running on roof of a train A against its motion (with velocity of 18km/h with respect to A)as observed by a man standing on ...
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1answer
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Relative velocity of a particle under uniform circular motion
The question is based on fairly simple mechanics principles but seems to have no definite answer.
Suppose there is a point particle A at a point X and around it another particle B in uniform circular ...
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1answer
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How is velocity at any point in a laminar flow constant in if the velocity profile in a laminar flow is parabolic?
Our lecturer said that velocity at any point in laminar flow is constant. But in another lecture slide (about flow velocity profiles), he also wrote that not all fluid particles travel at the same ...
