All Questions
103 questions
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Need help in understanding Tangential Acceleration [closed]
I am studying Circular motion and I am confused about tangential acceleration and tangential velocity. I am studying uniform circular motion and it says the tangential acceleration is $0$ in uniform ...
- 60.5k
0
votes
4
answers
304
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Confused about Kleppner explanation of acceleration in polar coordinates
In Kleppner's "intuitive" explanation of acceleration equations in polar coordinates he uses a geometric argument based on the figures on the left, but I don't get how the angles between the ...
CommunityBot
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0
votes
1
answer
213
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Is there anything like negative deceleration?
I kinda understand acceleration, deceleration and negative acceleration but does anything like negative deceleration exist?
CommunityBot
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0
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2
answers
414
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Why does tangential acceleration become 0 when the velocity is max? [closed]
I know that tangential acceleration equal to zero when the circular motion is uniform, but why is it equal to zero, when the velocity is max or min? Because there is no relation between the value of ...
- 12.9k
4
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2
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Is there a relationship between the magnitude of the velocity and acceleration vector?
Given a path, how do the magnitude of the velocity and acceleration vector along the path correlate? I am confused due to the fact that the acceleration is the change of velocity over time and in ...
CommunityBot
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9
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5
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Is there a scalar acceleration?
The magnitude of Velocity is simply Speed.
On the other hand, the magnitude of Displacement seems to be a simpler idea than Distance.
And the magnitude of Acceleration is not the change of Speed over ...
- 907
6
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2
answers
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Terminology for time derivative of speed (not velocity)
Is there any standard terminology for the derivative of the magnitude of velocity with respect to time (suitable for use in first-year Calculus)? The word ‘acceleration’, in its technical sense, is ...
- 907
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1
answer
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Components of velocity in projectile motion [closed]
I came across this question in my physics textbook (Gr12) and I was hoping someone could explain the solution to me
A ball is thrown horizontally off a building at $8.2\,\text{m}/\text{s}$. At a ...
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2
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49
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Equations of motion for constant acceleration
I read that the equations of motion for a constant acceleration can be represented in a scalar form as well as a vector form, but what's the need to do them in vector form what extra can we do by ...
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1
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49
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Finding radial acceleration from $xy$ vector cordinate [closed]
I know that is a silly question but i cant figure it out.
Suppose we have
$$ \textbf{R} = A i + B j $$
and want to find the radial acceleration.
We know that the radial acceleration is
$$ \ddot{r} -...
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3
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Why is it wrong to find centripetal acceleration using change of velocity over change of time?
This question asks to find the centripetal acceleration by giving the initial and final velocity over the change of time.
As shown, my book combined two rules to find the acceleration. I utterly ...
- 213k
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1
answer
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From where does the expression of the tangential accerelation come from?
I've seen so many times that the expression of the tangential acceleration is known to be: $$a_t=\ddot{s}$$ but from the expression of the acceleration in spherical coordinates, in the tangential ...
- 414
2
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1
answer
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(Circular motion) Acceleration is given, so why asked for more? [closed]
The full question is below.
A car starts from rest and moves around a circular track of radius $32.0\,\text m$. Its speed increases at the constant rate of $0.500\,\text{m/s}^2$.
(a) What is the ...
- 213k
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1
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43
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Are terms tangential acceleration and normal acceleration only used for instantaneous velocity?
Are terms tangential acceleration and normal acceleration only used
for instantaneous velocity?
CommunityBot
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1
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9
answers
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Why is acceleration variable in uniform circular motion?
Acceleration is the rate of change of velocity. In the uniform circular motion the acceleration is produced due to change of direction of the velocity(the magnitude remains same). The direction is ...
3
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4
answers
909
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Having some trouble with acceleration in polar coordinates
So, I solved a question about acceleration in polar coordinates, but most people in my class (Classical Physics, first year at university studying Physics) disagree with my answer. So the question is ...
- 9,461
2
votes
5
answers
1k
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Acceleration and motion can be in different direction?
I'm not getting what acceleration concept is and how it relates to motion and how motion and acceleration can be in different direction? And what's behind the concept of negative and positive ...
- 907
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6
answers
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If a body moves along a path (any path, not just circular) with constant speed, is it's tangential acceleration necessarily zero?
If a body moves along a path (any path, not just circular) with constant speed, is it's tangential acceleration necessarily zero?
I could only find general proofs for the case of circular motion and ...
- 2,740
6
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4
answers
838
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How can I write the vector form of this equation, $a = vdv/dx$?
My Physics teacher was deriving the 'Work-Energy Theorem' for a single particle in the class; where after doing the vector addition of all the forces acting on the particle, he put the resultant of ...
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1
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1
answer
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What does the dot product of the velocity vector and acceleration vector give me?
I am currently working with some velocity and acceleration vectors and I am a bit unsure about how to interpret the results. Consider the fact that I have 3 points 1.(x1,y1) @ t = 0.0s, 2.(x2,y2) @ t =...
CommunityBot
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2
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4
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910
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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 ...
CommunityBot
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3
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3
answers
845
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Physical significance of the terms of acceleration in polar coordinates
How do I get an idea, or a 'feel' of the components of the acceleration in polar coordinates which constitute the component in the eθ direction?
from what I know, $\vec a= (\ddot{r}−r\dot{θ}^2) \hat ...
0
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2
answers
358
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Circular motion equivalent in three dimensions [closed]
Are there equations or even a concept of circular motion/tangential acceleration/centripetal acceleration in three dimensions? Maybe something called "spherical acceleration"? or am I just ...
- 14.1k
0
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3
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244
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Why does Taylor take the derivative or only $r \bf{\hat r}$ for the velocity/derivative of the position vector?
Why does Taylor take the derivative or only $r \bf{\hat r}$ for the velocity/derivative of the position vector? If the position of an object in Polar coordinates is given by (r, theta), why is the '...
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2
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267
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What exactly is happening to acceleration when direction changes?
As direction changes i know that acceleration occurs but what exactly is happening to it, is it increasing acceleration, decreasing acceleration, constant acceleration, negative acceleration or ...
- 920
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2
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229
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Scalar term for acceleration [duplicate]
Consider the following definitions:
Distance is the magnitude of the displacement
Speed is the magnitude of the velocity
X is the magnitude of the acceleration
Is ...
- 213k
0
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0
answers
55
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What do you call $ \frac{d^2 r}{dt^2}$ in polar coordinates? [duplicate]
In polar coordinates, one finds centripetal acceleration as:
$$ a_c = \frac{d^2 r}{dt^2}- \frac{v^2}{r}$$
Where $|r|$ is distance from center to particle, $v$ is tangential velocity.
My question is ...
- 28k
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3
answers
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Why does solving the differential equation for circular motion lead to an illogical result?
In uniform circular motion, acceleration is expressed by the equation
$$a = \frac{v^2}{r}. $$
But this is a differential equation and solving it gets the result $$v = -\frac{r}{c+t}.$$
This doesn’t ...
0
votes
2
answers
353
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Why isn't tangential acceleration just always 0?
This is probably a very stupid question but I can't help me.
Tangential acceleration is $\vec{a_t}=\frac{dv}{dt}\frac{\vec{v}}{v}=\frac{\vec{v} \cdot \vec{a}}{v} \frac{\vec{v}}{v}$. Since $\vec{a}$ is ...
Buzz♦
- 17.1k
0
votes
1
answer
457
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Calculating 2D acceleration vector direction to most quickly reach a point
I am currently writing a game where you fly a starship in 2D space. In a given timestep, the ship has the ability to accelerate at constant rate in any direction. The player can specify a point at ...
- 39.3k
3
votes
3
answers
727
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Proof of $a = v^2/r$ using similar triangles
The book states that the ‘change in velocity’ triangle and the displacement triangle has the same angle theta.
But I don’t get it? How can we prove that the two triangles will have the same angle?
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1
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2
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159
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One object moves along the cycloid at a constant rate, how about its acceleration? [closed]
We know that the parametric equation:
$$x=R(\theta+\sin(\theta))$$
$$y=-R(1+\cos(\theta))$$
and the constant velocity $c$.
How do I prove that the acceleration of the object in the $y$ direction is ...
- 16.4k
0
votes
0
answers
72
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Acceleration in polar coordinates
Is transverse acceleration always perpendicular to the normal acceleration, in polar coordinates?
- 213k
1
vote
2
answers
788
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How do I get the total acceleration from 3 axes, in negative?
For a project, I'm working with acceleration data recorded by triaxial accelerometers. This means that I have accelerations in the x, y, and z axes. I found the almost exact same question from a few ...
- 9,359
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3
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471
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What is correct definition of tangential acceleration?
Is tangential acceleration the rate of change of magnitude of velocity
OR,
Is it simply the rate of change of velocity?
I am asking this because I am sort of confused, because there is no tangential ...
- 135k
1
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2
answers
115
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Why isn't tangential acceleration just $a$?
If the tangential acceleration is $\mathrm d|v|/\mathrm dt$ then isn't it just the magnitude of the acceleration of the object because $\mathrm dv/\mathrm dt$ is acceleration?
- 2,666
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1
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For an airplane moving north from some latitude (say $30^{\circ}N$), why does rotation of the Earth cause an increase in apparent drag?
I'm not able to understand the answer to this example:
Example 10 from the Curtis Orbital Mechanics text book :
An airplane of mass $70 000\ \mathrm{ kg}$ is traveling due north at latitude $30^\circ$...
- 213k
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1
answer
129
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Why intuitively is the tangent vector the derivative of velocity of position with respect to their modulus?
When trying to find the tangential velocity, many textbooks define the tangent direction as one of the following:
or
Intuitively, why is the tangent vector the derivative of the position with ...
- 1,496
2
votes
7
answers
4k
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The direction of the velocity of a body can change when its acceleration is constant. How is it possible since acceleration is a vector quantity?
As we already know that acceleration is a vector quantity which means that it has both direction as well as magnitude. It can also change given any one of the two or both (magnitude and direction) ...
- 30.2k
9
votes
3
answers
2k
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Is centripetal acceleration almost perpendicular to velocity or it is exactly perpendicular to velocity?
In all the derivations of centripetal acceleration that I have seen so far, the direction of acceleration is said to be perpendicular to velocity but I think it's not exactly perpendicular to velocity ...
- 1,462
0
votes
1
answer
146
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Do accelerations add the same way velocities add in non-relativistic mechanics? [closed]
Can you add and subtract constant accelerations?
CommunityBot
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3
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2
answers
312
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Motion with constant speed and constant acceleration magnitude
I was reading this and this posts. From what I gather
In 2D: Constant speed $||\dot x||=const$ and constant positive magnitude of the acceleration $||\ddot x|| = const$ imply circular motion.
In 3D: ...
- 1,918
0
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1
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114
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Average velocity and acceleration
I know to obtain the average of some vectors I compute the mean of the one dimensional components of each vector and constitute the average vector. My question is : why is this untrue for average ...
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5
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Acceleration vector at an extremum
A skier moves along a ski-jump ramp. The ramp is straight from point A to point C and curved from point C onward. The skier speeds up as she moves downhill from point A to point E, where her speed is ...
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2
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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 ...
- 1,588
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1
answer
531
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Proving that acceleration perpendicular to velocity only changes it's direction [duplicate]
In a recent class, I learned about centripetal acceleration and that if a body moves in uniform circular motion the direction of velocity continuously changes implying presence of an acceleration. My ...
Buzz♦
- 17.1k
3
votes
2
answers
105
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Which is the centripetal term here?
In spherical coordinates the acceleration can be written as
$$\textbf{a} = \dot{\textbf{v}} = \ddot{r} \hat{\textbf{r}} + \dot{r} ( \dot{θ} \boldsymbol{\hat{\theta}} + \sin θ \dot{\phi} \boldsymbol{\...
- 58.6k
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1
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Equation for four-acceleration
Wikipedia states that
$$ \begin{align} \mathbf{A} =\frac{d\mathbf{U}}{d\tau}
&= \left(\gamma_u\dot\gamma_u c,\gamma_u^2\mathbf a+\gamma_u\dot\gamma_u\mathbf u\right) \\
&= \left(\gamma_u^4\...
- 12.9k
-1
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2
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380
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When do you add or subtract vectors? [closed]
so I have a question here:
An airplane travelling initially at 240 m/s[28° s of e], takes 35 s to change its velocity to 220 m/s[28°e of s]. what is the average acceleration over this time interval?
...
- 213k
0
votes
1
answer
125
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Apply acceleration that is always opposite to the velocity
I have 2 functions for the $x$ and $y$ components of the velocity of an object ($z$ should always be $0$ in this case)
$$V_x(t)=v_{xi}+\int_0^ta_x(t')dt'$$
$$V_y(t)=v_{yi}+\int_0^t(-g+a_y(t'))dt'$$
...
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