# Tagged Questions

The change in position of an object relative to a frame of reference. DO NOT USE THIS TAG just because the question contains motion! Almost all physical systems contains motion. Hence it is often a poor way to classify a question to use this tag.

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### Describing the motion of a point-mass [on hold]

Consider a point-mass moving around a fixed point on a circle with radius $r$ with constant angular velocity $\omega$. At a certain moment of time, the connection is removed, and the point-mass flies ...
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### Dynamics particle motion around ellipse [closed]

For particle motion at constant speed around an ellipse with a major axis of 4 inches and a minor axis of 2 inches the ratio of the acceleration at pt. A to B is?
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### Inclined plane, circular motion and the friction

Suppose we have a cylinder on an inclined plane of mass $m$ and radius $R$ moving without sliding (so that $\varepsilon = a/R$). Why is the friction $F$ causing the circular motion sometimes lower ...
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### About using screw in air compression and air Engine [closed]

I want to use screw to build compressed air engine, as following image As I designed, this screw rotate in a tube My Question is: How successful this idea? Note: If this question not related to ...
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### Calculating estimated HP from velocity, auto weight, and constant acceleration

I am working on a simulation program that runs theoretical performances of different cars and was wondering if there is a way to estimate the HP at any running RPM? the problem is (and this may be me ...
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### Motion of a rigrid body: Why is motion only a compostition of two forms: rotation and Translation?

If you are in a 2-D space the motion of any rigrid body is composed of 2 different things, namely rotation and translation. If you are in 3-D space the motion of any rigrid body is also composed of 2 ...
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### Can a Chaotic Pendulum be made Continuous?

Can a Chaotic Pendulum be made continuous? I mean, Is there any Method or any Arrangement for a chaotic pendulum to Oscillate forever? (never stop its motion)
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### Is there always motion, when force is present? Is all motion vibration?

Even when you are seated in a chair, the chair is pushing up on you and you down on the chair (manifesting in the form of ~650N). While there is no obvious observable motion, is it not possible that ...
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### Can a characterization of “inertial motion” be expressed in terms of interval ratios?

Consider a "material point" $A$ having taken part in the two distinct events $\varepsilon_{A J}$, and $\varepsilon_{A Q}$, as well as in additional events "inbetween", such as any event ...
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### Can there be force without motion?

I am confused. Can you have a force or tension without motion? Take for instance two robots with jet packs connected via a cord, each is flying in opposite directions. The tension of the cord is ...
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What kind of motion would a (preferably dimensionless for simplicity) body do if the force acted on it was proportional to the semi-derivative of displacement, i.e. m \frac{\mathrm{d}^2 ... 2answers 51 views ### What causes the random movement of particles inside a conductor? I'm reading about currents in electricity right now, and it was mentioned that even if there's no electric field inside a conductor, charged particles inside are still undergoing random movement. I ... 2answers 87 views ### What is the difference between 'flow' and 'move'? I just met with a very basic question.(Might even sound silly!) My textbook kinda says(not exactly), 'Whatever flows is a fluid'. That got me wondering because we are creating a whole category of ... 5answers 3k views ### Can an object reverse its direction of acceleration even though it continues to move in the same direction? Can anyone please explain me on this matter along with day to day examples? 1answer 36 views ### If an area remains at temperature 0 Kelvin would the area be frozen in time? If an area is at 0 kelvin, I am guessing that there is no motion. Without motion in an area, will it not look as if time has stopped? 0answers 45 views ### how to calculate acceleration? [closed] The problem is as follows. A searchlight casts a spot of light along the face of a horizontal wall located 100m above from the searchlight. It rotates at a constant \omega of 4rads/s. Determine the ... 1answer 36 views ### Can the thermal energy in an object be aligned, creating a thermal jerk? Thermal energy is related to the speed at which atoms vibrate, therefor thermal energy is a form of motion. In a stationary object, all of these vibrating atoms 'impact' each other in such a way that ... 0answers 67 views ### snails moving on a sphere [closed] I am trying a variation of snails moving in an equilateral triangle. Suppose that you have 6 snails arranged on the the surface of a sphere such that they are equidistant from each other. All the ... 1answer 64 views ### Question about pendulum I came up with this problem by myself: How much force do I need to make a pendulum revolve? Now I imagined that the force \vec{F} must be enough to make the pendulum swing until half of the ... 1answer 84 views ### Angular distance Vs Angular displacement Are the two terms - 'Angular distance', and, 'Angular displacement' interchangeable for a uniform circular motion? 1answer 59 views ### Pendulum Confusion This text in my book is pretty confusing:With my emphasis A simple pendulum is a heavy point mass (bob) suspended from a rigid support by a massless and inextensible string. This is an ideal case ... 1answer 368 views ### Why do electrons move towards regions of lower potential? Can someone explain why electrons move from high to low potential regions in quantum mechanics? By the way, what is the very definition of this potential? Moreover, how does this generalize to other ... 2answers 466 views ### Why do two equal-and-opposing forces each do work on a moving object but not on a stationary object? Consider a point-mass m having constant velocity but undergoing influence from two forces, F_1, F_2, having equal magnitude but opposite directions. Because the forces' magnitudes are equal, I ... 2answers 83 views ### Non-uniform circular motion, computing the angle There is an object moving in circle, with this law: \alpha = -k^2 \theta  With $\alpha = \frac{ d \omega }{dt}$, and $\omega= \frac{d \theta}{dt}$, $\theta$ = angle, $k$ positive ...
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If a photon hits a 'perfect' mirror (with no environment interference) would the mirror move a bit?
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### Two vehicles moving in a line with different accelerations

Let two similar vehicles starting at rest in a straight line (with a distance of $D$ between them) have time-varying accelerations in the same direction. If both of them have similar time varying ...
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### Shock Absorber - Bus - Not Uniform

Imagine a empty bus/lorry travelling at high speed over the "speed brake", why is that only rear seat is heaved relatively high compared to the fron seat?
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### rectlinear motion with constant acceleration [closed]

Friends, this is a numerical homework problem. I tried my best to solve it but my answer is not matching with the one given at the back of the text book. Please help me out: A motor car moving at a ...
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### Displacement inside the moving Object

Suppose say a person is standing over the moving bike and he jumps while bike is moving, bike will move forward & person will land in same point at which he jumped, relative to earth position ...
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### Blueshift and increase in energy!

Imagine that there is a car and it is not moving but its headlights are on. There is a wall in front of the car but is very far away. Right now energy is being used only in switching on the ...
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### Inclined plane problem

FOR THE GIVEN PROBLEM AND SOLUTION BELOW 1) The problem statement, all variables and given/known data: A student pulls on a box up an incline of 10 degrees. The student pulls with a force of 180 ...
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### Motion of rigid body system in absense of work

In the absence of work on the system, is there a closed form equation for the motion of a set of constrained rigid bodies (let's say, using Revolute (ie: simple pivot) constraints)? If the bodies are ...
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### Mass Effect on Slingshot Motion?

For my physics class (I'm a high school student), we created slingshots. Our task is to predict the distance a projectile, launched from a slingshot using surgical tubing, would land. We aren't given ...
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### Exertion from swinging on a playground swing

I've read about how by tilting one's body one changes one's center of mass while swinging on a playground swing, and thereby increases the energy of the swing. But I would like to get a better sense ...
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### Need clearing up on vector decomposition in motion physics

I've been pursuing physics on my own, and I need something cleared up. Say I have two arbitrary objects, I have their velocities, I know when the collide, I have their normal vectors, etc. I know ...
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### What is empirical mean of centripetal acceleration

We have this formula for centripetal acceleration - $a = v \frac{d\theta}{dt} = v\omega = \frac{v^2}{r}$ but in case of usual acceleration i know that speed in $t_1 = v_0 + a \cdot (t_1 - t_0)$ but ...
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### Second law of thermodynamics and motion

The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems spontaneously evolve toward thermodynamic equilibrium—the state of ...
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### Does $y$-motion really have nothing to do with $x$-motion?

I am watching a Physics 1 for physical science majors on coursera.com, and in one of the concept tests there is a question that goes like this; "A bullet is fired horizontally from a rifle on the Moon ...
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### Does a heavy body move with the slightest force on a frictionless surface?

If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = ...
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### Problem Of Lazy Fish [closed]

Fish achieve neutral buoyancy (so they don't have to swim constantly to stay in place) via a swim bladder. A swim bladder is a little internal sack that they can inflate/deflate with air, which ...
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### Is projectile trajectory on Earth affected by the fact that it isn't a singular point?

So in high school physics, we were told that projectiles traveled in a parabola, but Google searches have said that it's more like an ellipse, since the Earth isn't flat. However, I was thinking that ...
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### Two formulas for a particle's acceleration

While on a class my teacher was taking about particle's motion in space. At some point she said the following: Consider that the particle's path is described by a curve in space defined by the ...
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### What would happen if an unstoppable force hits an immovable object? [closed]

I realize that the question a rather large paradox, but I do wonder if such a thing were true what would happen, assuming that neither of these "objects" can be destroyed by each other?
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### Circular motion problem? [closed]

I am learning about circular motion and not quite sure how to approach this particular problem. Any help would be greatly appreciated! A particle moves along a circular path over a horizontal ...
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### g as a function of Theta

I slide an object down a ramp of a certain length, which is inclined at a certain angle $\theta$. It reaches the bottom in time $t$. Assuming that no forces act on the object other than gravity and ...
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### According to Newton's third law, why don't Action and Reaction make equilibrium? [duplicate]

According to Newton's third law, Action and Reaction are equal and in opposite direction. If both forces are equal and in opposite direction then why they don't make equilibrium and void the effect of ...
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### Projectile motion, what is the relation between initial angle and speed at a given distance [closed]

I am trying to understand the relation between the initial angle of a projectile and its initial speed, given that the distance this projectile will travel is fixed and at the same height as the ...
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### Air resistance of a general shape object

I'm trying to code a simple physics simulator in C++ but I'm stuck on the air resistance issue. Surfing the Internet I only find a drag coefficient for very basical area shapes when the air is ...