# Questions tagged [acceleration]

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

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### Is the acceleration pseudo-force the same as a gravity wave from my surroundings?

If I were in my spaceship floating around in interstellar space within the Milky Way ... If I pointed my spaceship toward Andromeda and pressed the throttle to 19.16m/s/s for 1s then I'd get thrown ...
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### What is the sum of forces equation in curved spacetime?

I've been thinking about the Sum of Forces equation and the fact that gravity isn't really a force. So what is the proper way to think about this equation when dealing with objects in a gravitational ...
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### Kinetics of three moving particles attached to each other

Please refer to the image below. It is a screenshot of page 132, Chapter 13: Kinetics of a Particle: Force and Acceleration of the book Dynamics 14th ed. by R.C. Hibbler. Then refer to my question ...
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### What happens when the centrifugal force and Coriolis force combine?

Imagine someone is walking on a merry-go-round as it spins. Let's say the merry-go-round has a painted circle on it that is concentric with the outer edge of the merry-go-round and the person walking ...
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### Is relativistic velocity “implicit” a slower velocity?

I don't wan't to go in a big mathematical approach here but more of a kind understand some implications of special relativity. Since a object from a steady observer is time dilated and length ...
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### Mechanics accleration question and kinetic energy

I am really confused by this and I don't know why: Take the Earth to be spinning at 100,000 m/s at the surface. If I throw a ball on earth at 1m/s then its true velocity is 100,001 m/s Therefore, ...
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### Kinetic energy and acceleration of two bodies (easy) [closed]

I am really confused by this and I am not sure what assumption I have made that is wrong. KE $= \frac{1}{2}m v^2$. Consider a system of a BOX and a BALL and they both have a mass of $2 kg$ each: ...
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### What is the acceleration-time graph for a bouncing body? [closed]

So suppose a ball is dropped from a point above the ground. Taking the point from where the ball is dropped to be the initial starting position, what would be the acceleration time graph of the ball. (...
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### Feeling heavy in an upward accelerating elevator - is it a pseudo force?

In an elevator accelerating upwards, a person weighs "heavier" on a scale. The normal force can be expressed as $N=m(a+g)$, a being the upward acceleration. In this case, is $ma$ a fictional ...
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### What is meant by “pseudo forces are mathematical corrections in non-inertial frames”? [closed]

I have read in several posts that "pseudo forces are mathematical corrections in non-inertial frames" that enable Newton's second law to hold true. How is this "correction" related ...
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### Change In Proper Length After Acceleration? [closed]

A train has length $L$ whilst at rest in a station - this is a proper length. It undergoes a homogenous acceleration (each particle of the train moves in exactly the same way) until it reaches a ...
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### Is an EMF observed by a constantly accelerating loop the moment it is stationary to an electric charge?

Suppose I had a positive charge $+q$ fixed at the origin $(x,y,z)=(0,0,0)$. The coordinate system is that of the charge's rest frame. Now suppose I had a circular loop with a radius of 1 whose axis is ...
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### Does the SUVAT equations of motion (Kinematics) come from some differential equation?

Wikipedia says about the equations of motion that; "If the dynamics of a system is known, the equations are the solutions for the differential equations describing the motion of the dynamics.&...
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### Photoelectric Effect and Acceleration

My question relates to the photoelectric effect. Namely: why is a photon not produced by the photoelectric effect? If an electron gains a certain amount of kinetic energy from the incident photon, do ...
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### Calculating displacement from acceleration (intuitively) [closed]

If I say acceleration of car is constant at $4\; \rm m/s^2$. Then isn’t it that it covers $4\; \rm m$ in $1\; \rm s$ with velocity $4\; \rm m/s$. Then in $2\; \rm s$, the velocity is $8\; \rm m/s$. ...
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### Is it ever possible to have zero motion but non-zero acceleration? [duplicate]

First of all , here is a definition of motion I found in Wikipedia: In physics, motion is the phenomenon in which an object changes its position over time. Motion is mathematically described in terms ...
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### $F=ma$ if $a < 0$

The equation $F= m\cdot a$ is known, but what if $a < 0$? Is the force exerted negative?
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### Definition of torque in the (possibly accelerating) centre of mass frame

My lecture note states that the torque in the centre of mass frame ($O^*$) of a rigid body is: $$\bf{G^*}=\sum \bf{r^* \times F}$$ where $\bf{F}$ denotes the real force that is producing the torque ...
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### How do I get peak deceleration from an acceleration graph?

I have a single axis accelerometer attached to a ball, which I'm dropping from a fixed height, with the single axis fixed adjacent to the ground. Assume the ball does not rotate during the drop. I get ...
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### Light in an accelerated system

I was just wondering what it would be like if there was a car moving forwards with some velocity in vaccum and someone was to shine a flashlight inside the car, would the speed of light appear faster ...
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### Understanding the spacetime diagram for an accelerated observer moving farther away

This video on the Twin Paradox shows the following spacetime diagram to explain the scenario. While accelerating back to Earth, the travelling twin perceives time on Earth as speeding up, which is ...
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### Does the Second Postulate of Special Relativity hold for non-inertial reference frames? [duplicate]

That is, does the invariance of the speed of light hold for accelerated observers?
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### Speed, acceleration, accelerating acceleration, etc. How do we know where to stop?

I am not a physicist. Suppose a body A is falling towards body B in a vacuum. We know that A's speed will increase. However, as A draws near to B, the force of gravity will increase so the rate at ...
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### Analysis of a spring-block motion when the point of suspension is accelerating vertically upward

I was taught to apply a "pseudo force", [which is equal to mass × acceleration (of point of suspension)] in the direction opposite to the point's acceleration and then proceed the way I ...
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### Doubt in the Equivalence principle [duplicate]

In the equivalence principle, being in an accelerated reference frame is equal to being in a gravitational field. So,now I can consider earth as an accelerating reference frame. But, if that is true, ...
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### What is the formula for relativistic acceleration?

$BACKGROUND:$ I was recently watching a youtube video about Unruh radiation:https://youtu.be/7cj6oiFDEXc In this video, the host said that we need to accelerate at $10^{20}m/s^2$ to raise the ...
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### Calculating the mass of an object in an Atwood machine system [closed]

Sorry if the title doesn't represent my question correctly, I'm just learning physics and so I don't know what a proper title would be to describe the problem. I would be more than happy to be ...
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### Mathematical framework for explaining why the equations of motion look different in non-inertial frames

How do the equations of motion look different in non-inertial frames? Is there a mathematical framework that we could use to explain this fact?
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### Did Galileo intuit Newtons Second Law and Law of Gravitation?

If Galileo had no idea of Newton's Second Law or his Law of Gravitation, how did he figure out that objects of dissimilar mass fall at the same rate of acceleration if their initial conditions are the ...
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### In rotational motion, why $a = rα$?

The formula of torque is given by $$τ= F*r = Iα,$$ while solving some questions I came across a question of rotating pulley where these two formulas were equated to find value of $α$. How $a=rα$? a ...
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### Why do the principles of physics get more complex when the frame of reference undergoes acceleration?

Why do the principles of physics get more complex when the frame of reference undergoes acceleration?
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### Understanding two instances of different time dilation

I needed clarification as to two aspects of time dilation which seem distinct for me. Consider an observer inside an accelerated rocket and another observer outside of it. The outside observer will ...
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### What will be the direction in which these masses accelerate and move?

I've worked out the accelerations of each of the masses, as asked in the question, but I'm struggling with the intuition of it all. I understand that mass C will move down, and so the pulley will move ...
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### How should I interpret this relativity scenario?

I am having a bit of trouble understanding the point of the following relativity scenario. Imagine two freely floating rockets (side by side) of height $L$ in outer space. The rockets have a light on ...
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### Electron gun power consumption

The power consumed by the electron gun can be roughly calculated as P = V * I with V the acceleration voltage and I the electron current. In order to reduce the power consumed from battery, why are ...
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### A weird question about the cosmic speed limit [closed]

The cosmic speed limit is 299792458 m/s $(c)$. According to our current physics, if anything with positive mass will start to accelerate then the object will get arbitrarily closer to the speed of ...
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### Calculations of Earth falling into the Sun if it suddenly stopped orbiting? [duplicate]

If the earth stopped orbiting the sun, it would be pulled by the Sun's gravity and fall into it. How much time it will take is tricky as force is inversely proportional to square of distance. So I ...
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### Is this assumption reasonable?

In physics book which I use right now proposes a simple deduction for drag equation. Almost every part of it is nice. But when deducting, it says: Whenever object hits an air molecule (which we assume ...
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### Average velocity of rocket [closed]

A rocket is accelerating straight up from the earth's surface. At $1.15$ s after liftoff, the rocket clears the top of its launch platform, $63$ m above the ground. After an additional $4.75$ s, it is ...
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### The gravity-acceleration equivalence principle doesn't seem like exact equivalence. Is there something I'm missing?

Suppose I'm trapped in a box, and the box is $3\ \mathrm{m} \times 3\ \mathrm{m} \times 3\ \mathrm{m}$. I designate one vertex to be $(x,y,z)=(0,0,0)$ and the opposite one as $(x,y,z)=(3,3,3)$. I'm ...
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### Computing the $x$-$y$ position of a vehicle for constant acceleration

I want to very simplistically plot the $x$-$y$ position of a vehicle in 2D that can accelerate/brake and drive a constant speed while turning etc. The basic equations for determining the position for ...
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### Why are the seat belts designed the way they did? [closed]

I understand the importance of seat belts in vehicles. Since our body is moving at the same speed as the car, there should be something holding us tight in our seat when we step on the brake. Most 3-...
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### How can we be sure, that the dot-product of the four-vectors $U$ and $A$ in special relativity is zero?

I'am currently taking class in relativity and in the book that i have it is said that the four-vectors of velocity and acceleration is zero. I know that the invariance of the velocity is $-c^2$. Is it ...
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### What is correct definition of tangential accleration?

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 ...
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### Didn’t understand constraint relation here

2nd image is the way solved in book but not mine. I didn’t get that why $x_2$ is acc of block of mass 2 kg and why $x_2$ is comparable with block of mass 2 kg. $x_2$ is the length of string for mass 2 ...