Questions tagged [acceleration]
The rate of change of velocity of a body per unit of time.
2,317
questions
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How to calculate the proper acceleration (as a 4-vector) in general relativity?
I am trying to derive some equations which will let me simulate the motion of a spaceship in different geometries of spacetime. Suppose I know the metric and Christoffel symbols at the location of the ...
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0answers
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Relative acceleration of fermions?
Let's say I want to know the relative acceleration between $2$ particles in quantum mechanics which obey the Hamiltonian $\hat H$:
$$ \hat H = \frac{\hat p_1^2}{2m} +\frac{\hat p_2^2}{2m} + \hat V(...
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6answers
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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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4answers
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Newton’s second law of motion
In the equation $\vec F = m \vec a$ is the acceleration vector always in the direction of the force vector, I mean why can’t they be in the opposite direction? Will this relationship break down in ...
8
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6answers
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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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3answers
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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 $...
16
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8answers
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Why does mass limit acceleration?
If a force of $10\,\mathrm{N}$ is applied to different objects of different mass in empty space, in the absence of gravity, why do lighter objects accelerate faster than heavier objects? Why does mass ...
2
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4answers
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Tension in a string for different acceleration in each end
Say a regular string, with mass, is held by two persons in each end and they are in running in different acceleration in the same direction. Will there be any tension as different ends have different ...
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1answer
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Apparently the initial speed is 50ms^-1. But I keep getting 10ms^-1, am I missing something? [closed]
An object is projected vertically upwards at time t = 0. Air resistance is negligible. The object passes the same point above its starting position at times 2s and 8s.
If g = 10 m^s–2, what is the ...
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0answers
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What is the magnitude of acceleration of both blocks? [closed]
A solid disk of mass M and a radius 3R is attached to a thin hoop of mass M and radius R such that the two objects would rotate together. A block of mass M is attached to the large solid disk via a ...
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4answers
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Should not we apply pseudo-forces all the time as the Earth is a non-inertial frame of reference?
Clearly, the Earth is accelerating (as it has centripetal acceleration), and thus it is a non-inertial frame of reference. Then, why don't we use pseudo forces all the time? My teachers told me that ...
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velocity and acceleration [closed]
a)A cyclist lets her bike accelerate down a slope with constant gradient, at constant acceleration.
She passes point A, then 4s later passes a point B 32m away.
Another 2s later she passes a point C a ...
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vote
3answers
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Relativistic Accelerating Frame (non-inertial frame)
One way to resolve the Twin paradox is to count in the effect of acceleration when velocity suddenly changes. I am therefore searching for a relativistic version of "accelerating frame" or ...
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1answer
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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'...
0
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1answer
38 views
Kinetic energy of spacecraft appears to violate conservation of energy [duplicate]
We have a rocket in Space that accelerates with 10m/s². Our engine requires one Unit of Energy each second, while expelling neglible amounts of mass¹.
Well assume the rocket has a mass of 100kg aswell ...
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2answers
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1g acceleration, speed and gravity
Let's assume a spaceship is at rest and that it increases the acceleration from 0 to g m/s in 1 second and that it then continues accelerating at 1g for an indefinite length of time.
This means that ...
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0answers
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Can I use an accelerometer to measure the velocity of a car in a curve?
I am making an application that is used to measure the velocity, it has an accelerometer that measures the component acceleration in the XYZ-axis. When the car is moving just straight the measurement ...
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4answers
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Why do pseudoforces always act in opposite direction to acceleration?
Why are the pseudoforces felt by bodies inside an accelerated frame of reference opposite to the acceleration of the frame? I know that it is true by observation, but would wanna know why exactly. Is ...
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3answers
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Experimental evidence for $F=\frac{dp}{dt}$
Newton's 2nd Law says $\vec{F}= \frac{d\vec{p}}{dt}$ .
In a constant mass system this becomes $\vec{F}=m\vec{a}$. Answers to why $F=ma$ can be found here.
However, in a variable mass sytem (see ...
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0answers
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Bow and Arrow problem '2' [closed]
Several days ago I posted the next question....Bow and Arrow problem.
At the beginning the question got 3 downvotes but after a certain period it stabilized at equal number of downvotes and upvotes... ...
1
vote
2answers
448 views
My question is about the concept of acceleration [closed]
What would happen to the velocity of an object if it is given an initial acceleration of 2 meter per second per second in a case if there is no dissipating force such as gravity, air resistance or ...
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vote
2answers
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Why does two objects with different weights fall at the same time, taking air resistance to be negligible? [duplicate]
For instance, since weight is given by mass x gravitational field strength and assuming both objects have the same gravitational field strength and the only changing variable is its mass, why do they ...
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0answers
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What is the English phrase for “ loi de composition des accélérations” in French. ( Trans. “ composition of accelerations law”)
I'm looking for details regarding the derivation of a formula called in French" loi de composition des accélérations" ( " composition of accelerations law").
This law allows you ( ...
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vote
2answers
53 views
Does the $\rm s$ squared in acceleration $\rm m/s^2$ have a geometrical interpretation? [closed]
Is there a geometric interpretation of $\rm s^2$ in $\rm m/s^2$ as an actual square? Is it right to see the time forming a square like there is an actual square of side 2 in 2 $\rm m^2$?
If that's ...
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4answers
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Is the force initially exerted on an object the same it will exert on another?
If I exert a force on object A and it collides with object B. Does object A then exert the same force I initially exerted on it if it was at that time at rest?
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1answer
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Physics of Striking in Combat Sports
I was reading a blog post about the "physics of muay thai kickboxing" (https://heatrick.com/2013/10/13/the-science-of-muay-thai-lesson-1/) in which the author states that the main ...
0
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1answer
53 views
What is physically changing from velocity or acceleration to force and their vector components?
Here is question with two pulleys.
https://physics.stackexchange.com/questions/342861/why-is-velocity-of-the-mass-v-cos-θ-why-not-2v-cos-θ
Its clear that $u =\frac{v}{\cos \theta} \tag{1}$
But now ...
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3answers
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Can a very fast centrifuge affect the path of a light beam?
I am thinking the answer is "no" since you can't see time dilation (I have read) in a centrifuge. But why would a light beam not be bent by what is felt like gravity to someone inside the ...
3
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2answers
53 views
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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6answers
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Constraint equation for wedge block system
Q) What is the constraint equation of motion between wedge A and block B relative to A?
My Approach :
If we displace the wedge A by $x$ distance then the block B should have a net displacement of
$$x(\...
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0answers
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Will there be a component of acceleration perpendicular to the surface along which a particle moves?
A particle is sliding in a cone maintaining contact with it all the time. Analyzing the situation in spherical coordinates I was able to find that in the total acceleration of the particle there will ...
14
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14answers
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Is no acceleration a cause or consequence of no net force? [closed]
If a body is moving with constant velocity, or is at rest, then the net force on it must be $0$. If the net force on a body is $0$, then it must be moving with constant velocity or must be at rest.
Is ...
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2answers
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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$"?
0
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2answers
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If I throw an object upward will its acceleration change or it will stay constant at $-g$?
I mean if, for example, I throw a rock upward, its acceleration will always be $-g$ or it will be $-g+a$ because I apply a force on the object when I throw it? (without considering friction)
0
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1answer
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Apparent weight: fictitious forces [closed]
I have this exercise that I have solved
Mark wants to calculate the acceleration of the lift in his building using a scale and the
using a weight balance and using the laws of apparent forces in non-...
0
votes
3answers
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Centripetal and centrifugal acceleration in an athletics raceway (for example)
I consider this question and the answer of the user @Bob D in this link: Centripetal and Centrifugal acceleration/force. When an athlete runs round a curve in the atletic track he will be subject to ...
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0answers
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Does friction in a tube with a string in it cause the string's tension to increase?
If I were to swing a string horizontally above my head with a mass on the other end, through a tube, and the tube had friction compared to the ideal frictionless situation, would it cause the string's ...
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3answers
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Newton's Laws of Motion, Pulleys, Rope and tension
I was solving some questions to apply my concepts, and I came across the atwood machine and pulley block problems.
Consider the following for example:
The pulley is massless and frictionless, string, ...
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vote
3answers
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Newtonian physics and equivalence principle: a doubt on acceleration and gravity
First of all, the famous Einstein's elevator experiment is quite clear in my head, both of versions.
But now, consider the following:
Suppose then you wake up inside a car that is traveling in ...
0
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1answer
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Force Applied Jumping Off Chair
For physics my teacher wants me to calculate the force applied jumping off a chair. He gave no extra details and I have no clue where to begin. We are learning about work and energy at the moment so ...
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3answers
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A question on Newtonian dynamics [closed]
Imagine a trolley moving at constant velocity thus, no external force and momentum are conserved. Then at x kg/s sand is falling on that trolley and the velocity of the trolley will decrease as ...
1
vote
1answer
54 views
Gravitational field of a moving object
Here's a simple scenario:
Let's say, that there are 2 stationary planetoids of equal mass on the Earth's orbital motion path, placed at equal distances from Earth just like on the image below:
Will ...
0
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1answer
53 views
Calculate the force of an air rifles projectile
I have an air powered rifle and I would like to find a way to calculate the amount of force it produces as well as its velocity. The air rifle can be pumped which increases the pressure which gives ...
1
vote
1answer
26 views
Force of Gravity and F=ma
Imagine a box on a table. It should have $F_g$ downward and $F_N$ upward.
(I do get that we have to add those forces.)
However $F=ma$ and the box's mass is constant.
How is $F_g=mg$ if the box's ...
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5answers
498 views
In a collision shouldn't objects of different mass have same acceleration?
Suppose two objects of different mass, A and B, collide with each other. Now, during the time of collision, they both apply forces on each other according to Newton's 3rd law. Therefore, their ...
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0answers
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Reference for Galileo's Law of Motion
It is stated in some places that one of Galileo's laws of motion is that two objects in free fall in a local gravitational field with different densities will hit the ground at the same time in a ...
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5answers
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Confusion about acceleration in rotating without slipping
We know that if there is a flat surface with friction, a ball rolling without slipping will conserve its energy, as friction does no work on the ball.
$$\Delta E = 0 $$
Because kinetic energy is ...
0
votes
4answers
145 views
Why can’t I use $F=ma$ to calculate the orbital path of a planet? [closed]
Why doesn’t gravitational acceleration over time predict the planet's distance from the Sun? Gravity is toward one point and over time you should be able to predict the distance.
If the planet is ...
0
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1answer
30 views
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 ...
0
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0answers
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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 ...
