All Questions
25 questions
0
votes
4
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107
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How can I detect when a car makes a turn using velocity vectors and account for speed?
I am trying to detect when a car makes a turn by analyzing its velocity vectors over time. Each velocity vector is represented as:
$$\vec{v_t} = (X_v, Y_v)$$
Currently, I calculate the change in ...
- 3
1
vote
5
answers
207
views
Speed and Velocity
Why did physicists develop the concept of velocity? I searched on the web, but I didn't get a satisfactory answer. All I got is that velocity has a direction whereas speed does not. Why do we need ...
- 19
8
votes
4
answers
2k
views
What does squaring a vector mean?
So,in the 3rd equation of motion,i.e $v²=u²+2as$,what does the square on the final velocity and initial velocity actually mean?And how does it make an effect on their direction?
suppose upwards vector ...
- 422
2
votes
4
answers
908
views
Mathematical proof for: Acceleration always orthogonal to its velocity changes its direction
Whenever I ask this doubt that how can force perpendicular to objects velocity can change its direction but cant change its magnitude I get proof for only the magnitude will be constant that is: no ...
- 375
1
vote
1
answer
94
views
Simple difference between module of velocity and time derivative of module of position [duplicate]
What is the conceptually difference between the two:
$$\frac{d|\vec{r}|}{dt}=\frac{\vec{r}\cdot\frac{d\vec{r}}{dt}}{|\vec{r}|}\neq|\dot{\vec{r}}|\equiv \bigg|\frac{d\vec{r}}{dt}\bigg|$$ ...
- 189
0
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0
answers
46
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1/velocity for higher dimensions
I have a somewhat basic question. I am sorry if it trivial.
Denote the velocity by $v=\frac{dx}{dt}$ suppose that $x \in \mathbb{R}^n$ and I want to parametrize $t$ in $x$ and compute $\frac{dt}{dx}$. ...
- 103
1
vote
6
answers
861
views
Is velocity a vector quantity? [closed]
I've read that velocity is a vector quantity. Then why do most of the people when stating the velocity of an object never use direction? Most of them usually say that 'a car is moving at a velocity of ...
- 837
0
votes
4
answers
721
views
Velocity squared confusion
As far as I know, a vector cannot be squared. Velocity is also a vector, though we have equation of motion, $v^2=u^2+2aS$. I am perplexed with $v^2$ here. What does it imply?
- 2,578
0
votes
3
answers
257
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Where does speed and velocity differ? [duplicate]
I'm in Junior High and I still have some confusion towards speed and velocity. They sound like the same thing, where some object moves in a given direction, but there is a difference from both topics.
...
user298882
0
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0
answers
91
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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 ...
- 1
1
vote
2
answers
1k
views
How can speed be the magnitude of velocity
Say speed is the magnitude of velocity then:
\begin{align*}
v &=\left|\vec{v}\right|\\
\frac{D}{\Delta t} &= \left|\frac{\Delta \vec{x}}{\Delta t}\right|\\
\end{align*}
since $\Delta t$ is ...
- 191
1
vote
2
answers
1k
views
Is instantaneous speed always equal to the magnitude of instantaneous velocity?
Is instantaneous speed always equal to the magnitude of instantaneous velocity? What about the infinitesimal time duration when the direction changes? How can it ALWAYS be equal?
- 23
0
votes
2
answers
743
views
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, $...
- 87
-1
votes
3
answers
214
views
Why was the concept of velocity created? [closed]
Why do we use velocity instead of speed for different physics problems?
I recognize how they are different but why use one over the other?
- 13
1
vote
7
answers
161
views
Is there centripetal acceleration with velocity of 5 m/s?
So if an object is moving at $5\ \mathrm{m\ s^{-1}}$ in a circle, is it accelerating?
Me and a friend are having a conversation about this.
5
votes
8
answers
7k
views
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_{...
- 223
-2
votes
1
answer
617
views
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 ...
- 105
0
votes
3
answers
3k
views
Tangential Velocity - vs - Tangential Speed
It's the first time for me to ask a question here.
Is there a difference between "Tangential Speed" and "Tangential Velocity"?
As far as I know, Speed is scalar quantity defined only with its ...
- 3
-1
votes
2
answers
5k
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What is the difference between $d|v|/dt $ and $ |dv/dt| $ & between $d|x|/dt $ and $|dx/dt| $? [closed]
Here, $v$ represents velocity vector and $a$ represents acceleration vector.
1
vote
1
answer
2k
views
Is value of speed equal to the magnitude of velocity?
For example: - suppose a body covers a semi-circle in $5$ seconds, then distance$=\pi * r$, where $r$ is the radius of the semi-circle. Displacement is $2r$ only. Then the value of speed is $[\pi * r] ...
- 11
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3
answers
2k
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Is centripetal acceleration based on speed or velocity?
I know that the formula for centripetal acceleration is $\ a_c = v^2/r$.
Does the $v$ represent the average velocity of the car which is the arc length traveled divided by the time? If the answer is ...
- 341
0
votes
2
answers
1k
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Why does centripetal acceleration have a magnitude?
Assuming that the magnitude of velocity is constant. Why does centripetal acceleration have a magnitude? Since acceleration is the rate of change for velocity and its magnitude remains the same ...
- 341
1
vote
2
answers
644
views
Magnitude of instantaneous velocity vs speed
Magnitude of instantaneous velocity = $|dr/dt|$ but this is not always equal to $ds/dt$ where ds is the infinitesimally small change in distance in the interval $dt$
Which one is speed?
- 1,106
-3
votes
1
answer
2k
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What is meant by negative direction of velocity? [duplicate]
What is negative velocity and negative direction of the velocity?
3
votes
2
answers
43k
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Difference between Speed and Velocity
What is the difference between Speed, Velocity and Acceleration? Could any one describe it pictorially?. I am more over confused even after investigating many times. I am unable to relate myself ...
- 133