# Questions tagged [kinematics]

The description of the movement of bodies by their position, velocity, acceleration (and possibly higher time derivatives, such as, jerk) without concern for the underlying dynamics/forces/causes.

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### Ackermann Steering Angle

Given the position of the vehicle ($x,y$) at different time points, the speed of the vehicle (m/s), the direction the vehicle is facing (heading — in degrees), the track width of the vehicle, and the ...
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### Are acceleration and velocity simultaneous? [closed]

I would think yes because, if a rope tied to a swinging rock breaks, the rock flies off in the direction that is perpendicular to the direction of the last instant of the acceleration. The ...
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### Distance travelled in free-fall

When an object is in free fall, we have: $$a(t) = g - \frac{c}{m}v(t)^2$$ where $g$ is acceleration due to gravity, $m$ is the mass of the object, and $c$ is the coefficient of air resistance. How ...
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### Hypothetical special relativity with mass conservation [closed]

I thought of this question while studying inelastic collisions in special relativity, where kinetic energy is converted into mass-energy. I was wondering if it's possible to formalize a version of ...
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### Why do three particles placed at the vertices of an equilateral triangle, moving along the sides, meet at the centroid?

I just read an example of vectors in my book which is confusing me. Three particles A,B and C are at the vertices of an equilateral trinagle ABC. Each of the particle moves with constant speed v. A ...
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### Can we do a thought experiment to prove that the horizontal and vertical motion of a projectile are independent of each other?

It seems really hard for me to grasp the idea that horizontal and vertical motion of a projectile are independent of each other. Intuitively I feel that they should affect each other. How can it be ...
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### Formula to determine acceleration based on constant energy input

I'm a software engineer building a simulator for train movement. What I would like to do is create an acceleration curve that's closer to reality. This is my thinking, which includes some ...
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### How is torque transmitted between inclined surfaces?

In the picture below, in a), a body K1 is pivotably attached to a bearing. My question is about the torque that results from a force exerted onto a surface of the body K1. A first force F1 applied ...
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### How to find tangential/radial/angular velocity for motion in any curve? [closed]

Is the radial velocity responsible only for changing distance between objects and the component perpendicular to it only for change in direction? If so why? Please try to give a different explanation ...
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### For circular motion in a vertical plane, why does Net Force = Centripetal Force?

I'm struggling with some of the concepts pertaining to the forces and acceleration associated with circular motion in a vertical plane (only concerned with what happens at the 'top' and 'bottom' of ...
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### Rotational motion from curved slope?

So I've learned for any slope with a sliding object, say a box, the speed at the bottom only depends on the height it was dropped from because of conservation of energy, assuming absence of friction ...
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### Does a constant 4-acceleration implies constant acceleration?

Before asking the question I explain here my line of thoughts: I'm almost sure that a constant acceleration $\bf{a}$ implies constant 4-acceleration $w^\mu$. So I assume constant acceleration, then, ...
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### Angular velocity as $r \to 0$

I know that angular velocity is defined as the rate of change of angular displacement and is related to tangential velocity via $$\omega = \frac{r\times V}{|r^2|}$$ My question is what will be the ...
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### Displacement vs. Distance

I'm new to physics, and I just learned what velocity is. From what I learned, velocity is, displacement/time. But, I'm confused about what displacement and distance is, and how is affects velocity. So,...
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### Average acceleration versus instantaneous acceleration

Does instantaneous acceleration also changes when direction of velocity changes. I know average acceleration does change.
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### Writing source four velocity for Lorentz boosted frame

I am trying to derive the source four velocity for Lorentz boosted frame. If the source four velocity for rest frame is denoted as $U^{\alpha} = (1, \bar 0)$, then how do I write this $U^{\alpha}$ for ...
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### Why does the Fluid inside a Water Balloon Continue to Move even when the Balloon Being Pulled has Stopped?

If there is a rubber balloon filled with water attached to a string, and the string is pulled in 1 direction, causing the balloon to also be pulled, why does the water inside continue to move even ...
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### Why can't some light ever reach earth? [duplicate]

Note: I'm a layman in physics. Excuse me if this question is a duplicate, I lack the knowledge in technical terms to find the answer to this by research (I've tried). Let's suppose there's a star ...