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

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32 views

Relating Initial velocity and acceleration to distance traveled up a ramp

This is the situation: I am conducting research on the ability of fin-fish to scale short wetted ramps for use alongside sea-lamprey barriers to allow non-target species to pass these barriers. We ...
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1answer
28 views

Net force equal to mass multiplied by acceleration of centre of mass [closed]

$F=ma$ if $a=0$ then definitely the net force applied will be also zero (0). then, in this case $m=F/a$. If both net force and acceleration(of centre of mass) is equal to zero (0). then, isn't mass ...
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0answers
36 views

How does Einstein's curved space time produce acceleration in a free falling object? [duplicate]

I never really thought much about all of this before so I'm definitely a newbie. Please excuse my ignorance. If I understand what I have read so far: if spacetime is curved time would click by at a ...
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1answer
30 views

Why is the acceleration of the center of mass is equal to 0 in this problem?

I don't understand why the center of mass' acceleration is equal to 0 when the center of mass should be moving as an external force is exerted on the cue ? Billiard Balls. Now we can go back and ...
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2answers
112 views

How to calculate acceleration from discrete samples of velocity?

I have a device that I made which is able to calculate distance moved and can determine time. I take samples of time every x distance. Giving me n velocity samples. I currently show the user 2 ...
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1answer
72 views

What is $\omega \times v$?

I found that equation in my textbook. It says that $\omega \times v$ ($v$ is velocity) is centripetal acceleration. But how is the equation derived?
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0answers
21 views

Do all objects free fall at the same rate regardless of their mass? [duplicate]

Is it true that all object will fall at the same speed in vacuum irrespective of their mass because the acceleration due to gravity of Earth is 9.8 m/s2. Then what happens to the gravitational force ...
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2answers
46 views

Force on a Massless String

Suppose we are just pulling a block with the help of a string which is massless. Now since the mass of the string is 0 the force exerted by us is transmitted without being diminished. So the equation ...
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2answers
30 views

How to calculate the acceleration, if the mass-center is not on the force-vector's line (2D)

In a 2D plane there is an object, whose center of mass is at the $P$ point. The mass of the object is $m$. We apply a force $\vec F$ at the point $A$. If the center of mass is on the line, defined ...
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1answer
86 views

How does acceleration feel compared to gravitational pull?

I was debating a variation of this Phys.SE question with a friend. The original question is: "If you had your eyes closed, could you distinguish between standing still on earth and being in a ...
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1answer
23 views

What is the minimal G-force curve in 2-dimensional space?

Given two parallel roads, which need to be connected, what shape of curve would produce the minimum overall horizontal G-force(s) on travelers? Is it a $sin$ or $cos$ wave? Is it a basic cubic ...
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1answer
74 views

Different forms of centripetal acceleration

For a circular motion centripetal acceleration can be expressed as $$a_{c}=\frac{v^2}{R} \hat{u_N}\tag{1}$$ Where $\hat{u_n}$ is the normal unit vector. Nevertheless in the expression for ...
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6answers
100 views

Elevator normal force

In the above case, the normal force exerted by the elevator on the box would be $= 10\mathrm{kg}\ g + 10\mathrm{kg}\ 5\ \mathrm{m/s^2}$, assuming $g = 10\ \mathrm{m/s^2}$, the elevator would exert a ...
1
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0answers
54 views

Determining the forces required to maintain a static center of mass position; one with velocity and one with acceleration [closed]

I'm having a bit of trouble wrapping my head around this conceptually. The magnitudes and directions of the forces on two of the particles are indicated. What are the magnitude and direction of the ...
-1
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3answers
57 views

How to show that distance travelled in the $n$'th time interval grows in arithmetic progression [closed]

$\mathbf Q.$ A car starting from rest and accelerating uniformly travels a distance $d$ in the first $n$ seconds and a distance $k$ in the next $n$ seconds. Prove that $ k=3d$ Attempt: $$d=(v_1)(n)$$...
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1answer
36 views

Infinite acceleration of bob in pendulum with no friction or air resistance

So i'm a bit confused about something. If we take a mathematical pendulum and we apply a force to it. We ignore all friction and air resistance and only consider gravity and the force applied to bob. ...
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0answers
33 views

How to derive velocity, distance from a changing acceleration?

I'm making a electronic device that is out of the scope of this site, but essentially it gives me acceleration readings every X microseconds. Given these samples of acceleration, how can I find out ...
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1answer
40 views

How to simulate an accelerometer in code

I want to write a simulation of an accelerometer (with a fixed X and Y axis in this case but with respect to a world coordinate frame) on a stick, rotating in a circle around a fixed point. From that ...
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1answer
59 views

Angular Acceleration of a Pendulum

I am trying to work out the mathematics behind the design of an old mechanical brake tester. The device sits in the passenger foot well of a vehicle and tests the brake efficiency. The device is ...
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1answer
20 views

Physics of Auto Crashes and Airbag Modules

I recently saw a post (that was pretty old) asking why we don't consider the jerk function more often in sciences that deal with impacts or sudden accelerations. The general belief was that impacts, ...
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2answers
61 views

Dynamics of swinging

My husband built a 20'-high tree swing, using 3/16"-welded-link chains to suspend it approximately 2' off of the ground. To our disappointment, pumping barely gets the swing going, with little height ...
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2answers
83 views

The two causes for the factor 2 in Coriolis effect

While reading this document on Coriolis effect http://empslocal.ex.ac.uk/people/staff/gv219/classics.d/Persson98.pdf, I saw the followig sentence Two kinematic effects each contribute half of the ...
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1answer
51 views

Contraction of a rotating system

Consider a system of two masses that rotates with constant angular velocity. When a force contracts the system the velocitie of the two masses increase. I understand this in terms of conservation of ...
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1answer
41 views

How do you know when to use kinematic equations as apposed to $v = d/t$ and $a = v/t$? [closed]

How do I know when to use v = d/t and a = v/t or d=vi+​1/2​​at^2 and vf = vi + at?​
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4answers
90 views

Question related to accleration due to gravity [closed]

What effect will be seen on the value of accleration due to gravity if radius of the earth is decreased keeping the mass constant?
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2answers
44 views

Acceleration due to conservation of angular momentum in absence of a force

I don't understand why the conservation of angular momentum can imply an acceleration, in absence of a force. Consider for istance planetary motion. The angular momentum $\vec{L}$ of the planets is ...
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5answers
197 views

Why do heavier objects fall faster on hills but not in straight drops?

All other things being equal, if a heavier object will roll at a higher speed down hill than a lighter one, because it's heavier with more mass, then how is it that dropped objects fall at the same ...
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2answers
51 views

Position, velocity and acceleration vs time graphs

I'd like to draw graphs of a vehicle and I have a position vs time table. I can set the points but how am I supposed to join them, straight or hyperbole ? If the object is accelerating which is yes ...
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2answers
62 views

Which formulas can be used instead of $\frac{1}{2}kx^2=\frac{1}{2}mv^2$, when we are solving a mathematical problem related to horizontal spring? [closed]

Let, contraction of a horizontal spring, $x$, is $4$ cm and mass of a bullet, $m$, is $10 g$. Spring constant, $k$, is $200 N/m$. When bullet leaves the gun, what will be the velocity of it? Can I ...
8
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1answer
147 views

Acceleration of particle “held in place” at $x = 1$ [closed]

The metric components in a two-dimensional spacetime are given in terms of the coordinates $(t, x)$ by$$ds^2 = -\cosh x\,dt^2 + dx^2.$$Consider a particle that is "held in position" at $x = 1$. What ...
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0answers
32 views

Centripetal acceleration in polar coordinates

$ \left( \ddot r - r\dot\varphi^2 \right) \hat{\mathbf r} + \left( r\ddot\varphi + 2\dot r \dot\varphi \right) \hat{\boldsymbol{\varphi}} \ $ I'm not convinced about the term $- r\dot\varphi^2 \hat{...
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0answers
109 views

Calculating travel time based on distance, velocities, acceleration, and jerk

Not much physics background so please bare with me. Say we have an object traveling on a straight line going from x to y. We know the starting velocity at x, the velocity when y is reached, the max ...
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2answers
78 views

Why does force cause acceleration?

Consider a ball placed on a smooth plane. If you take a plank made out of wood and whack it (apply a force on it), does it accelerate because First, the force compresses the part of the ball in ...
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2answers
58 views

Infinitesimal time intervals use

I've a question, that maybe will sound obvious, on the use of infinitesimal quantities. Consider the expression for the acceleration in non inertial frames. $\frac{d\vec{v}}{dt}=\frac{d\vec{v'}}{dt}...
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3answers
57 views

Physical interpretation of Coriolis terms in acceleration

Consider a reference frame which is rotating (for example on a carousel) and a steady inertial frame, with the same origin. $\vec{r}=\vec{r'}$ $\vec{v}=\vec{v'}+\vec{\Omega}\times\vec{r'}$ $\vec{a}=...
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1answer
79 views

“Spacetime tells matter how to move; matter tells spacetime how to curve” and acceleration in flat space-time? [closed]

John Wheeler stated "Spacetime tells matter how to move; matter tells spacetime how to curve." Does this contradict with the assumption that mass can be accelerated in flat space-time (see i.e. this ...
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3answers
51 views

Why the similarity in the Equations of Motion for Rotational and Rectilinear Motion?

These are the equations of motion given constant acceleration, for first rectilinear and then rotational motion. Rectilinear Motion: Rotational Motion: While the variables have changed, and the ...
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0answers
50 views

What kind of unit is $m^2s^{-4}$ in terms of gyro/accel?

Background While working on something in the field of avionics, I have discovered the following unit as part of an inertial-physics equation... $$m^2s^{-4}$$ I am trying to figure out the formal ...
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1answer
35 views

How to compensate a top-heavy platform [closed]

I have a small four-wheeled platform weighing 1.3kg with a height of 30cm. Its center-of-mass is located at 75% of the height, making it a little top-heavy. I empirically measured the angle at which ...
0
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1answer
31 views

Explanation of a Mechanical Situation [closed]

The box sitting on the table top has some mass $m$ (I would refer to the weight of the box just as $\mathbf{W}$), and its net acceleration which I call $\mathbf{a}$ is zero, for the time being. This ...
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1answer
70 views

Calculate constant acceleration needed to reach terminal velocity at specific time [closed]

I'm trying to find a way to calculate a constant acceleration given the following: One dimensional motion. The only forces involved are the force ($F_a$) caused by a constant acceleration ($a_c$) ...
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0answers
31 views

Kinematics - Non constant acceleration [closed]

A biker traveling the road is 100 km away from his destination, at t=0 (initial time). His speed, at the start point, is 100km/hour, and varies equalys to his distance from the final destination, ...
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5answers
245 views

Rapid (ac/de)celeration in relativity does what to inertial clocks?

EDIT (to clarify my question): I think some of the answers here are accounting for light travel time and telling me what I'd actually see on Earth's clock, so I've edited my first paragraph to ...
2
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1answer
47 views

How to get speed of a train without using GPS

How can I measure instantaneous speed of a train in which I am travelling without using GPS/location services? The train can start underground or can start from ground level (where GPS is available) ...
2
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2answers
73 views

Why was it difficult to walk in the same direction the train's acceleration, and easier the other way around?

The other day while I was walking in the same direction that the train was accelerating. Then I came across this question. Please if would answer it, I am very curious to know. But when I walked the ...
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3answers
58 views

Charge moved across a potential difference; where does the energy for emitted radiation come from?

Let's use an electron and a 1V potential difference as a mode. In school I learned that if the electron is at the negative end of the electric field, its potential energy is equal to the work that ...
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0answers
31 views

What is the equation for the position of a falling body as a function of time? [duplicate]

I know that near the surface of the earth a projectile's position follows a parabolic curve in function of time because the acceleration is constant (about 9.8 m/s2). However, acceleration ...
1
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2answers
47 views

Simple harmonic motion..direction of acceleration

To solve questions about simple harmonic motion, my book says $\ddot{x}$ (i.e. acceleration) is in the direction of increasing $x$, i.e. away from equilibrium. I don't understand why is this so, since ...
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1answer
25 views

Distance formula using initial velocity and acceleration

we know $S=ut+1/2at^2$. Now lets say my initial velocity $u=10m/s$ and acceleration be $a=5m/s^2$. In first second distance traveled $S^{_t=1}=10m$ as my speed is $10m/s$ and time is $1s$. In next ...
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2answers
114 views

Forces on wheels in an accelerating vehicle

Assume that a motorcycle of mass $m$ has two wheels that are equidistant from its centre i.e the force on each wheel is $mg/2$. If the motorcycle accelerates forward, will the two forces on each ...