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

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7answers
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Help understanding Bell's spaceship paradox

The problem statement of Bell's Spaceship paradox is this: Two spaceships float in space and are at rest relative to each other. They are connected by a string. The string is strong, but it ...
0
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2answers
173 views

Relativity and acceleration-acceleration

Presummary to save expert's time! (pls see below!) "In GR, is jerk relative?" As I understand it, "Special Relativity" (special meaning, specific limited situations) applies only for (in a word) ...
5
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5answers
1k views

High speed does not kill. Does acceleration do it ? or jerk?

In a recent question the OP asked why high speed will not kill us. The accepted answer, highly upvoted, stated very first that Speed doesn't kill us, but acceleration does. The second answer ...
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3answers
88 views

Power and velocity?

If $P=Fv$, power is constant and the power is the rate of change of kinetic energy, i.e. $$P = d(mv^2/2)/dt,$$ what must $v(t)$ be to satisfy this equation?
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0answers
61 views

Trying to model the acceleration of a system due to an impulse forcing function

My team and I are working on a design project to design/modify a device that can go on hikes for paraplegic/quadriplegic people. Here is the current design (not designed by us): We are thinking ...
0
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4answers
263 views

A question on force and acceleration

Q 1. Two bodies, $m_1$ and $m_2$, in contact with each other, are under constant acceleration $a$ in the same direction. Find the force exerted by $m_1$ on $m_2$. A similar question with my ...
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2answers
98 views

Determining Acceleration Based On Graph

I understand how to solve this problem, but I am unsure how to generate an equation for the graph (below). My current attempt involves using the mass provided along with the derivative of the line ...
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2answers
190 views

Perceived acceleration in an artificially modulated gravitational field

It's intuitive that while accelerating in a locally constant gravitational field, there is no perception of acceleration, since the body accelerates uniformly. What if a body were in a rapidly ...
15
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5answers
10k views

How fast would someone have to run to travel vertically up a wall?

I am currently doing a physics project on the effects of so-called 'super-speed'. I was wondering how fast you would have to run to vertically travel up a wall? That is, to negate the force of ...
1
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1answer
101 views

Confused about gravitational potential energy [duplicate]

So learning the concept of gravitational potential energy, my professor says that when lifting an object without any acceleration, the force we exert on the object to lift it is the same as the force ...
1
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1answer
336 views

How to model a very simple spinning wheel

First off, I'm not a physics person, just a lowly software engineer with below average math skills. What I've written is a simple animation of a spinning wheel using C++/GTK/Cairo. It allows the user ...
1
vote
1answer
736 views

For a massless pulley moving upwards with acceleration, is the upward force equal to the downward force?

Imagine a massless and frictionless pulley with two weights hanging either side of the pulley by a massless string. Like this except not attached to a ceiling Rather than being fixed to a ceiling, ...
2
votes
1answer
156 views

The 3rd derivative of the size of the universe?

We know the size of observable universe, that it is expanding, that expansion is accelerating. Does sufficiently precise data exist to determine at least the SIGN of the next (the 3rd) derivative? ...
0
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2answers
293 views

Orientation of a rocket going in a circle?

This problem is from my physics homework: A rocket is moving at constant speed in a perfect circle in deep space, far away from any planets or stars. The diagram below shows the circle the ship ...
0
votes
2answers
205 views

Converting velocity-time line to acceleration-time?

How would one find where the straight line on a VT graph is on an AT graph? For example in the above image, if I were to convert that into an acceleration-time graph, where on the y-axis would the ...
2
votes
0answers
206 views

Odd experiment results (electromagnetics)

Okay, a bit of background. So I'm working on a linear accelerator (you might know it as a Gauss rifle), and I had worked through the equations I thought I needed (Magnetic force, displacement, etc.) ...
0
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3answers
593 views

How does an electron undergoing uniform circular motion exactly lose energy?

One of the main reasons for the failure of the Rutherford model of atomic structure, it is famously stated, is that the electron undergoing circular orbit loses energy since due to its centripetal ...
0
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2answers
66 views

Constant vs increasing acceleration for reference frames

I was reading this webpage created by a professional physicist and was shocked regarding his statement on constant acceleration not being sufficient for producing the old "ball flies into the ...
4
votes
1answer
240 views

Does accelerating generate gravitons?

If gravity and acceleration are indistinguishable, then does that mean converting potential energy to kinetic energy generates gravitons... but only temporarily until you stop accelerating?
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1answer
159 views

Distance as a function of time where acceleration changes with respect to distance

I was thinking the other day about gravity. I know that acceleration in a magnetic field changes with respect to distance from the center of the field. So I was thinking, how would one find the total ...
1
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1answer
147 views

Do Photons Accelerate Upon Creation? [duplicate]

Of course the speed of light is constant relative to everything. Its frequency can change, but its speed is constant. Photons may be absorbed by atoms or release by atoms as energy, but as soon as it ...
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2answers
122 views

Does Centripetal Force Change Direction?

I have been struggling with this question that I have, "Does centripetal force change direction?" From every point, it points to the center. But if we draw its vector, we draw the tails from ...
1
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1answer
114 views

Gravity of the accelerated particle in General relativity?

Suppose heavy particle or body ("billiard ball") is accelerated with very thin and very rigid (not absolutely rigid) rod of infinitesimal (not zero) mass ("cue stick") Acceleration is constant in ...
1
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1answer
135 views

Accelerating beyond the speed of light? [duplicate]

Suppose you have a lot of fuel in your spaceship, in deep space - enough to accelerate at 1mss for a long time. What would happen once you are travelling close to the speed of light? Could you reach ...
3
votes
1answer
182 views

Units of acceleration & Newton's 2nd Law

I tried to use Newton's second law, $F=ma$, to calculate the acceleration of an object. \begin{align}\frac{F}{m}&=\frac{ma}{m} \\ a&=\frac{F}{m}=\frac{30\,\rm N}{1.2\,\rm ...
2
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1answer
1k views

Finding the acceleration given only an angle

This is one of my homework problems for a College Physics I course: Dana has a sports medal suspended by a long ribbon from her rearview mirror. As she accelerates onto the highway, she notices ...
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2answers
1k views

Derivation of the average Velocity formula with constant acceleration (using calculus)

I have been looking at $$ v_{avg} = \frac{v_{i} + v_{f}}{2}, $$ when the acceleration is constant, where $v_i$ is equal to the initial velocity and $v_f$ is equal to the final velocity. How can ...
3
votes
4answers
655 views

Is a causal relationship implied by Newton's 2nd Law?

Throughout my time learning physics I have been imbued with the notion that forces cause accelerations, period. Accelerations don't cause forces, and they aren't merely correlated phenomena. By ...
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1answer
217 views

How much fuel is needed for a constant-acceleration rocket?

My son and I have been discussing the concept of a constant-acceleration rocket, as described here and here. We're willing to assume advanced technology such as a fusion rocket, which, according to ...
0
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0answers
15 views

Help with Kinematics and trajectory [duplicate]

I am asking this again because it was closed and I didn't receive a response. So a baseball is hit with a velocity of 30 m/s at 42.6 degrees to the ground. A fielder who is supposed to catch the ...
3
votes
2answers
3k views

“Magic” Speed to Drive Over a Speed Bump: Myth or Reality?

A somewhat controversial aspect of speed bumps (sleeping policemen for those in the UK) is that they arguably cause more loss of life than they prevent by acting as a hindrance to emergency response ...
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1answer
183 views

A question about finding average velocity and average acceleration

I have trouble understanding the following problem's answer: Which of the following relations are true for any arbitrary motion in space? (a) $v_{avg}=\frac{r(t_2)-r(t_1)}{t_2-t_1}$ ...
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votes
1answer
251 views

Direction of radial acceleration same in circular motion?

I have a big confusion. There is a question in my book which basically says that a ball is tied to a string and rotated. and it asks me to tell whether the following statement is true of false. ...
1
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1answer
1k views

How to use accelaration data of moving object to calculate distance?

I read couple of similar question on this forum and few blogs on web, though I am still confused,I am determined to calculate object displacement using accelerometer data. So, I tried using ...
2
votes
2answers
734 views

If gravitation causes constant acceleration why moon does not fall into earth? [duplicate]

If moon travels with constant speed in one direction and earth gravitation causes constant acceleration in perpendicular direction why moon does not eventually fall into earth? I mean if gravitation ...
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1answer
306 views

Angular acceleration and linear acceleration

I have a small confusion. I learned very recently that all particles of a rotating body have the same angular acceleration but different linear acceleration (same for velocity as well). But how is ...
0
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2answers
806 views

A problem says : a car starts from rest and undergoes a constant acceleration. It travels 5 m in the…? [closed]

A problem says : A car starts from rest and undergoes a constant acceleration. It travels 5 m in the t interval 0 s to 1 s, find the displacement of the car during the time interval from 1 s to 2 ...
-2
votes
1answer
173 views

If it takes less than a year to accelerate to the speed of light at 1g why will it take the Voyager 10,000 years to reach Alpha Centauri?

Today I was doing my physics homework and there was a problem involving a space ship falling at 9.8 m/(s^2) to simulate gravity, and it asked how long would it take for the ship to reach to speed of ...
0
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1answer
229 views

Average acceleration when more than two different velocities occur [closed]

Suppose a car travels at 5m/s north for 5 seconds, it then turn east and travel at 7m/s for 10 seconds, finally it turns north east and travel at 10 m/s for 20 seconds. What is the average ...
0
votes
1answer
157 views

Finding Acceleration Force of Gravity on Rotated Accelerometer

Is it possible to calculate the force of gravity on the $x$, $y$, and $z$ readings of an accelerometer if I know the rotation of the sensor? If so, how would I do this? Sorry if I am doing this ...
2
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0answers
49 views

Alignment of a triaxial accelerometer [closed]

I was wondering if someone could explain the alignment issues associated with a tri-axial accelerometer. It measures acceleration in terms of $g$. I have read some literature but I am unsure about the ...
5
votes
2answers
5k views

The acceleration vector of a simple pendulum

In this picture the acceleration vector $\vec{a}$ points upward when the pendulum is halfway Click To see animated GIF But according to this picture, the force acts tangentially: Which means the ...
2
votes
4answers
2k views

Why is acceleration constant in this example?

I was shown this video by our professor: https://www.youtube.com/watch?v=8A7DiGzJUvg&feature=youtu.be And I do not understand why the acceleration is constant. Our professor told us that a freely ...
1
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1answer
298 views

Gravitational acceleration at half Earth's radius [duplicate]

What would be the gravitational acceleration at half at Earth's radius? Something tells me it should be proportional to the mass distributed in that part, but I am not sure. Of course, we assume we ...
1
vote
2answers
660 views

How can Excel be used to model the flight of a rocket? [closed]

Firstly, sorry for any silly mistakes or improper use of this website - this is my first time using it! I am trying to use Excel to model the flight of the Apollo 11 Saturn V rocket using the real ...
2
votes
1answer
169 views

Eddy Currents: Relationships between thickness and deceleration

This is probably a question with a very simple answer, but I want to make sure before I write too much. I'm doing an investigation on Electromagnetic fields, in particular eddy currents and how they ...
0
votes
6answers
599 views

Does large acceleration have to cause damage to the human body?

My whole life, I've heard that large accelerations cause damage to humans (e.g. g-forces in space movies). However, after reading about general relativity, it seems to me that a strong force which ...
1
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2answers
219 views

What is the relative acceleration of a projectile fired at in a low gravity vacuum?

This question is to end an old argument. Given a (space) vehicle with an acceleration of X, and projectile with an acceleration of 2X (rocket, not bullet), what would the relative acceleration of the ...
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0answers
49 views

How forces work during hammerthrow

I am not sure if I understand how forces work during hammerthrow. From my understanding athlete works with Fmuscle force on a ball and rotate it and a ball works with equal opposite force on an ...
1
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3answers
153 views

How to differentiate between rotating frame and linearly accelerating frame?

Two friends, $A$ and $B$ are part of an experiment. $A$ is placed in a closed box and made to accelerate in free space at an acceleration $g$. $B$ is also placed in a closed box, but is made to rotate ...