All Questions
Tagged with acceleration kinematics
704 questions
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Centripetal force equation doubt
In a centrifuge, $a_c$ should be constant. If $m$ increases, the $r$ will increase in order to maintain a constant $a_c$.
Constant centrieptal acceleration is given by
$a_c={ v^2 \over r}$
and $a_c = ...
- 2,578
2
votes
3
answers
344
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Should the stars of a relativistic binary system have tangential acceleration?
Should the stars of a relativistic binary system have tangential acceleration?
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0
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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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1
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Calculate point of rotation start for spacecraft with linear acceleration
I hope someone can help me with my problem.
I would like to move a spaceship from A to B. I want the spaceship to accelerate to the middle of the path, then rotate 180° and then decelerate.
Now the ...
- 1,813
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5
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Instantaneous acceleration vector toward the concave side of a curved path
Why does the instantaneous acceleration vector of a moving particle always point toward the concave side of a curved path? My college textbooks mention this as something obvious, without further ...
- 213k
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5
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Stopping Distance (frictionless)
Assuming I have a body travelling in space at a rate of $1000~\text{m/s}$. Let's also assume my maximum deceleration speed is $10~\text{m/s}^2$. How can I calculate the minimum stopping distance of ...
CommunityBot
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Sign of acceleration from position-time graph
These three graphs are from my textbook. It states that the acceleration in 1) is positive, 2) is negative and 3) is zero and can be told by looking at the slope.
What I understand from the graph is ...
- 2,578
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1
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Angular vs tangential vs centripetal acceleration of a non-rotating object [closed]
I was presented with a physics problem which asks to determine the maximum angular acceleraion. Unsure of how to do this, I did some research and came across the terms angular, tangential and ...
- 39k
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6
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Is four-acceleration spacelike? How to show this? What does it mean?
Consider a four-velocity $u_\mu$ that satisfying $u_\mu u^\mu=c^2>0$. Differentiating w.r.t the proper time $\tau$, we get the equality $a_\mu u^\mu=0$ which means the four-velocity and four-...
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3
votes
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: ...
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3
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Is there any explanation from special relativity regarding the speed of a fly inside a car?
I have faced a scenario mentioned in this Question.
There was a fly inside my car and I was travelling so fast. shutters are opened in the car. I observe that when I slow down and accelerate, there ...
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1
answer
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How is the acceleration faster than the speed of light? [closed]
The acceleration of a particle in an electric field given to me by a calculator is 175881998679 m/s squared - isnt that faster than light? How?
- 213k
-2
votes
2
answers
73
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Understand accelerometer value
I'am using an accelerometer, so if I put my accelerometer on a table for example I got gravity 9.8, I have this result by this formula : $\sqrt{x^2+ y^2 + z^2}$, ok so now if I lift quickly my captor ...
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2
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How can there be negative acceleration when the object’s velocity is increasing?
If the velocity of the object changes from -2m/s to -6m/s, then its velocity has increased and therefore the acceleration must be positive.
But using the formula for acceleration (or while plotting it ...
- 1,537
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1
answer
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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4
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392
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Are there two normal forces here?
In this question the normal force direction on the collar was determined to the left, while there is a possibility to be to the right direction also since the collar contacts the rod in both ...
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3
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How to deal with functions of kinematic quantities not defined in terms of time?
How do I deal with functions of kinematic quantities which are not defined with respect to time?
For instance, given acceleration as a function of velocity or displacement, how would I go about ...
- 213k
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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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Is such a situation realistically possible where $v$-$t$ graph is continuous but $a$-$t$ graph is not?
Taking for example $v = \cos(t-1)$ from $t \in [0,1]$ and $v = e^{t-1}$ from $t \in (1,\infty)$ and $t \ge 0$. At $t = 1$, the function shifts from cosine to exponential, but remains continuous since ...
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5
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Why is the acceleration along $x$-axis during projectile motion equal to 0?
Why is the acceleration along x axis during projectile motion equal to $0$?
And if it is equal to $0$ then the object shouldn't stop along x-axis after vertical velocity reaches $0$ along $y$-axis.
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Motion of rocket in flat space
Assume a rocket in hypothetical flat space which is at rest with thrusters off.
The role of thrusters is to help the rocket accelerate.
If the rocket has to move with uniform velocity it will first ...
- 30.2k
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4
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295
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What happens when a body is moving in a non-uniform circular motion?
What happens when a body is moving in a non-uniform circular motion where tangential acceleration is also present?
Will it continue to move in circular path or it will take an elliptical orbit?
- 213k
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1
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Should I take initial velocity and acceleration due to gravity positive or negative in motion in 1 dimension?
I was studying motion in one dimension, my sir taught that when a body is thrown upwards from the ground it will have a negative initial velocity and negative acceleration and when it will be falling ...
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1
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Is Initial velocity of an object zero after it reaches maximum height and starts free falling under 1 dimension?
I am studying motion in 1 dimension in kinematics and doing gravitation part. I was doing a question in which a ball is thrown upward from a tower of height $20\mathrm{m}$ with a speed of $5 \mathrm{m}...
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2
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Generalization of straight line motion under constant acceleration
My question is that, we all know the three equations of straight line motion under constant acceleration,
\begin{align}
x & =x_{\rm o}+v_{\rm o}\,t+\tfrac12 \mathrm a\,t^2
\tag{1d-a}\label{1d-a}\\
...
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Can position be derived from acceleration in practice?
We know that acceleration is the derivative of velocity, and velocity is the derivative of position. But does that mean that we can find position from acceleration in practice (as opposed to in theory ...
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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 ...
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1
answer
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Acceleration vector at an acute angle to velocity vector
What will be the description of motion of particle if acceleration vector always make an acute angle with velocity vector?
I know that if acceleration vector makes right angle with velocity vector ...
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1
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530
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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♦
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0
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66
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Deceleration to terminal velocity under constant force
I am modeling an object under a force $F$ that diminishes with distance but is considered constant at small time intervals. I am also incorporating a drag force $D$ that is opposite the direction of $...
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1
answer
458
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Expressing acceleration in terms of velocity and derivative of velocity with respect to position
we know that
$$a = \dfrac{dv}{dt}$$
dividing numerator and denominator by $dx$, we get $$a=v\dfrac{dv}{dx}$$ provided that $dx$ is not equal to zero or instantaneous velocity not equal to zero
when I ...
- 213k
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3
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Acceleration of a Bouncing ball when it hits the ground
The conceptual problem I am having difficulty with is something like this:
If a bouncy ball is dropped from some height $h$ and rebounds to a height of $0.75h$ in some time $t$ (for example), what ...
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Regarding Uniform Acceleration [closed]
Please give some basic intuition or hint to solve this question. I'm getting stuck.
The star of a distant solar system explodes as a supernova. At the moment of the explosion, a
resting exploration ...
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2
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Velocity time graph analysis: what does a concave downward $v$-$t$ curve mean?
This is a screenshot from the lecture about the analysis of various velocity-time graphs I was watching.
I understand that
the concavity of velocity-time graph will tell about the
increasing or ...
- 213k
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6
answers
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How to find the falling time of an object when acceleration is not a constant? [closed]
Let's say we are throwing an object from the surface of the earth, this object reaches 70,000km with initial velocity of $10713 \mathrm{m}/\mathrm{s}$ until it reaches the peak high , the g value at ...
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6
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Can acceleration depend linearly on velocity?
Is it possible that acceleration may vary linearly with velocity. Is it practically possible, if so is there a practical example of it?
By integration I was able to verify that for the above case to ...
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3
answers
63
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Motion in a plane situation
There is something weird I find about the following situation. Suppose a particle has the $X$-coordinate $= 2+2t+4t²$ and $Y$-coordinate $= 4t+8t²$. So it's velocity in $X$ is $2+8t$ and velocity in $...
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Can accelaration of a falling mass be positive when upwards direction is positive? What am I missing?
As shown in the figure:
(+) direction is upwards
displacement is y
time=t
Let's say that $ y=30-5t^{2} $ , thus the second derivative will give acceleration as -10 which is (-) as expected.
Now let'...
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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{\...
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2
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Confusion Unit of Acceleration
I have been reading Newtonian mechanic but I got confuse in defining the unit of acceleration that "Why is the unit of acceleration $m/s^2$"?
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1
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Solving an infinitely decaying propelling system [closed]
I am a HK secondary school student who is taking part in the HKPhO training in my school. I was doing some training questions and struggled with this question:
A car with initial speed $v_0$ is ...
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0
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Finding velocity from total linear acceleration
I am new to this platform so I apologize if I am asking question in an incorrect manner
I am not a physic student hence the reason I am here to clarify some of my doubts. I have this idea of using an ...
- 2,509
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1
answer
174
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Average and Instantaneous Acceleration [closed]
This example comes in my Physics book, but I don’t understand one part of the equation.
The velocity of a particle moving along the $x$ axis varies according to the expression $Vx = 40 - 5t^2$, where $...
- 213k
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0
answers
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Is there a limit to $\frac{d^nx}{dt^n}$? [duplicate]
There is already a question on the limit of acceleration($\frac{d^2x}{dt^2}$) and we all know the limit of velocity($\frac{dx}{dt}$) which is $c$ or the speed of light.
My question is a generalized ...
- 213k
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votes
1
answer
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How to calculate constant acceleration required to move an object by a distance $d$ in time $t$? [closed]
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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1
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Where is the direction of acceleration in a body moving in 1 dimension? [closed]
like where is the direction of acceleration if a car is moving in a straight line or if an object is thrown upwards (its direction if acceleration) ?
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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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1
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Can the acceleration of a decelerating particle be positive? [closed]
let's say you have friction on a surface that makes particle A decelerate constantly at $-0.75 ms^{-2}$. when you draw a velocity-time graph to graph this you will get a line $y=mx+c$ with a negative ...
- 213k
4
votes
2
answers
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Why the formula of kinetic energy assumes that the object has started from an initial velocity of zero?
According to my physics textbook, the formula of kinetic energy is:
$$
W = \frac{1}{2}mv^2
$$
Where $m$ is is mass of the object and $v$ is the velocity of the object. The equation is calculated from ...
1
vote
4
answers
1k
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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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