# Questions tagged [acceleration]

The rate of change of velocity of a body per unit of time.

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### Acceleration when motion is constrained by rope

The following is a question form HC Verma (Newton's Laws of Motion). I am not able to understand that if we consider the body of mass $M$ to move downwards with acceleration $a$, then why would the ...
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### What is a negative force actually?

If we find the force for a decelerating object (let's say a car on a road), we'll see that the force is negative as in it’s in the opposite direction of the motion of the object. I wanna know what ...
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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) ...
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### Acceleration and Reference Frames

If I'm in a car and hit the gas, an outside observer on the ground sees my car accelerate to some speed, and given the mass of my car and the horsepower of my engine, this obeys Newton's second law. ...
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### Maximum value of angular acceleration

In a video of Prof. Walter Lewin, in which he is talking about the maximum value of angular acceleration, he says that it does not imply that the angular acceleration is zero if the angular velocity ...
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### Use of net acceleration in circular motion

We know there are two types of accelaration in circular motion, one is centripetal acceleration and the other one is tangential acceleration. The resultant of these two is the net acceleration $a$. ...
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### Velocity as a function of time [closed]

Deriving velocity as a function of time. A particle of mass $m$ has velocity $\dot{x}$ at $x = 0$ and $t =0$. It travels along $x$-axis subject to drag force given by $F(\dot{x})=-c\dot{x}^{3/2}$ ($c$ ...
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### How to explain the accelerated expansion universe

enter image description here Some textbooks describe accelerated expansion with an H value, as shown in the two figure above. It is said that the H value is accelerated because it is smaller in the ...
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### What is behind a Rindler horizon? Or is there nothing?

Most of my friends say that a Rindler horizon is an artefact of acceleration. Space continues behind it. A few of my friends say that the Rindler horizon is an event horizon and a particle horizon. ...
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### How can we calculate $g$ force in this maneuver?

How can we calculate $g$ force in this maneuver? We are not dealing with conventional maneuvers like level turn or loop so what equation used to calculate g force in this maneuver? What about other ...
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### Can a relativistic rocket ever dilate time enough to be practical? [duplicate]

It seems the best shot for humans to visit other stars is a relativistic rocket, such as the hypothetical 1g rocket, which would dilate time in order for the mission to be completed in the crew's ...
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### If General Relativity were only a theory of accelerated frames, would it contain the Equivalence Principle?

In Relativity: the special and general theory, Einstein motivates General Relativity by the need to extend relativity not only to inertial frames, but also to accelerated frames. The laws of physics ...
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### Acceleration of a rotated point using rotation matrices [closed]

I am trying to calculate the acceleration of a point using rotation matrices and struggle to get my head around them. Imagine an inverted pendulum which can rotate about its x-axis but not any other ...
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### Why is force equal to mass into acceleration?

If I'm sitting on a chair I'm exerting a force on it but my body isn't even moving so it doesn't even have a velocity. Then how can it even have a change of velocity i.e, acceleration?
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### Can extreme acceleration (or space expansion) disintegrate a proton?

I have read this question: It worked in a similar way to dark energy but was so strong it would easily tear atoms apart Attractive higgs force and inflation And this one: Within mainstream physics ...
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### Regard Two Objects As One

I was trying to solve the following exercise (apologies in advance for potential mistakes in terminology); illustration will be attached below: An object with mass $M$ is placed upon a frictionless, ...
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### Accelerated through a potential difference

Say a electron is accelerated through a potential difference of 10v established between two points A and B 1metre distance apart. Then would i only be able to say that a electron is accelerated ...
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 $a_c = ... 2answers 197 views ### Quantum gravity in an accelerated frame of reference It is said that we can't study quantum gravity because gravity is a weak force. But gravity and acceleration are the same. Why can't we study quantum gravity in a strongly accelerated frame of ... 3answers 437 views ### Where does pseudo force act at? It is known that, to apply Newton's laws in a non-inertial frame, we use the concept of pseudo force. We also know that force is a bound vector. Hence, is there a general way to determine where the ... 3answers 261 views ### Should the stars of a relativistic binary system have tangential acceleration? Should the stars of a relativistic binary system have tangential acceleration? 1answer 26 views ### Acceleration as$\frac{D\vec u}{Dt}$in the case of unsteady flow In the book of Acheson, it is stated that the material derivative$\frac{D\vec u}{Dt}$can be considered as an acceleration of a "fluid element" - which is something the author never defined,... 2answers 81 views ### Cylinder rolling on inclined plane Let’s consider a rolling cylinder on an inclined plane with some friction. We knew that$\alpha R=a$, where$\alpha$is the angular acceleration of each constituent particle and$R$is the radius of ... 1answer 115 views ### Do accelerations add the same way velocities add in non-relativistic mechanics? [closed] Can you add and subtract constant accelerations? 2answers 42 views ### The optimal time to start decelerating a craft landing directly on a planet I was playing around with Kerbal Space program and I came across this issue that I hope somebody could help me with. Suppose there is a craft accelerating radially toward a planet due to gravity, with ... 2answers 63 views ### Angular momentum in rotating non-inertial reference frame I know in inertial reference frame rigid body we can write$L=I\omega$where$L$is the angular momentum of the rigid body,$I$is the moment of inertia and$\omega$is the angular velocity of the ... 1answer 35 views ### Leaking freight car problem - Help understanding a solution I'm dealing with the leaking freight car problem: A freight car is loaded with a water tank. The mass of the freight car and the filled water tank is from the start$m_0$. At time$t=0$a horisontal ... 3answers 77 views ### How Does a Rocket Even Go Up? [closed] The earth pulls all bodies towards it at$9.8\ \mathrm{m/s^2}$. I would like to imagine that the ground is accelerating up at$9.8\ \mathrm{m/s^2}$(just as an analogy). So this means that a rocket ... 2answers 107 views ### What is the time derivative of the linear velocity vector$\vec{v}\,(t)$? If$\vec{v}\,(t)$denotes linear velocity, we can then write$\vec{v}\,(t)$as$|v(t)|\hat{v}$. My question is what is$\displaystyle\frac{d\vec{v}\,(t)}{dt}?\$ The answer I have seen to this question ...
In general relativity, I know that $$u^\mu=\dfrac{d x^\mu}{d \tau}$$ and $$a^\mu=\dfrac{d u^\mu}{d \tau}$$ where spacetime coordinates of a particle are a function of proper time and they are not ...