# Tagged Questions

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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### Initial speed in homework problem [closed]

This is a homework question. I tried to solve it, but failed. I had to translate this question, so please forgive me if it is poorly worded. In this question you can ignore the atmospheric ...
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### At what point does force stop translating an object and start purely rotating it? [duplicate]

At what point (or distance) from the axis of rotation, does force applied on a rigid body stop translating and purely rotating the body? Can such a point even exist? Does the body always have to ...
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### Why does a plane look like it's slower than a car?

Recently, I was in a car and noticed a plane in the sky. What was interesting was that the plane seemed to go slower than my car because I passed the plane. Is there a physics reason to this?
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### What are the equations for motion with constant jerk?

Every one knows the three famous equations for motions with constant acceleration . But what if the motion were having a jerk? How should then be the equations for motions? How can I find them?
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### Quick question on free fall of 2 objects [closed]

I am trying to work through a problem, that is basically telling me that two objects were dropped from a building, one was thrown 2 seconds after the previous object, and I have to find out how long ...
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### What acceleration to use in this problem?

A balloon starts rising from the ground with an acceleration of 1.25 m/second square. After 8 second, a stone is released from the balloon. Find the time for stone to reach ground, distance ...
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### The dimensional formula of distance travelled in $n$th second

I read that the dimensional formula of distance traveled in $n^{th}$ second is same as that of velocity. Okay, the formula for the distance traveled in $n^{th}$ second is $s_t= u+\frac{a}{2}(2t-1)$ ...
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### i can't detect what wrong have i done in a kinematics problem [closed]

a question was given to us in assignment which was as follows A person moves 20 metres towards north then 30 metres towards east and then moves 30 x 1.414 metres towards south west. The whole ...
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### Increase in velocity by loss of mass? [closed]

A trolley of mass 300kg carrying a sand bag of 25kg is moving uniformly with speed of 27km/h on a frictionless track. After a while, sand starts leaking out of a hole on the floor of the trolley at ...
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### Measuring the velocity of a pendulum using the width of the bob

I did an experiment on pendulum motion and in the method it says use the following equation to measure the velocity of the pendulum: $$v=\frac{W}{t}$$ where $W$ is the width of the pendulum bob and t ...
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### How does this chair move?

I have a chair like this(shown in figure). I was kneeling on the part where we sit. I just gave a sudden push to the part where we rest the back, without moving my legs. I found that the chair is ...
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### Calculate kinematics of body movement from the set of spatial coordinates

Short intro I have a set of 3D (x,y,z) spatial coordinates of arm movement obtained using motion capture system. The example set of such coordinates looks like this (rounded up): ...
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### why does perpendicular motion to the direction of someone' s approach does not affect the distance between them

I was reading about the the four turtles/bugs math puzzle Four bugs are at the four corners of a square of side length D. They start walking at constant speed in an anticlockwise direction at all ...
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### Motion of a rod struck at one end

Imagine a strong metal rod of uniform density and thickness floating in a weightless environment. Imagine it lies on an X-Y plane, with one end (A) lying at 0,0, and the other end (B) at 0,1. Then it ...
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### Is it possible to calculate specific velocities from acceleration?

I'm trying to understand a sample problem from a current (published 2011) high school physics textbook, but I really think the question is flawed. The task is to convert an acceleration-time graph ...
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### Doubt concerning centripetal acceleration

What is the centripetal acceleration and angular velocity of a child located 8.2 m the center of a carousel? The speed (size of the tangential velocity) of the child is 2.1 m / s A train moves in a ...
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### Force required to send ball in set trajectory

If I have a desired 2D trajectory where I know the desired speed of my ball and desired path, and a ball that starts at (x=0,y=0), how can I calculate the required force / point at which the force ...
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### Can we observe two different events occuring at the same point?

I was wondering a situation. Suppose a train is moving with a certain acceleration. It turns on its front light at a certain time, and it's back light say t s after. But to a inertial, or non ...
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### Acceleration of a particle moving along a straight line

If a particle moves along a straight line, then can we say that the acceleration should be zero? and if not, then why? If the equation of the motion is linear, then the velocity is constant and if ...
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### How to get these SUVAT formulae?

When learning kinematics, I have learned these three formulae $s=1/2(u+v)t$ $s=ut+1/2at^2$ $v^2=u^2+2as$ s = displacement u = initial velocity v = final velocity t = time a = acceleration My ...
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### Photon energies after neutral pion decay

I am trying to find the photon energies of the decay $\pi_0 \rightarrow \gamma\gamma$ and their dependence on the pion energy $E_{\pi}$, its initial velocity $\beta$ and the scattering angle between ...
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### Problem in deducing the equations of motion using indefinite integral

As we know, antiderivative or indefinite integral is the function the derivative of which gives the actual function. Let $F(x)$ be the derivative of $f(x)$ ie. the instantaneous rate of change of ...
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### What is the relation between kinetic energy and momentum? [closed]

If kinetic energy is doubled, what happens to momentum? Is it also doubled? I've tried working through the formulas for each but keep getting lost. $$KE=\frac{mv^2}{2}$$ $$p=mv$$ so if ...
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### Problem with formula for parabolic motus

I know that the path made by an object thrown in air with velocity $v_0$ with an angle $\alpha$ is: $$y=x \cdot\tan \alpha - \frac {gx^2}{2v_0^2\cdot \cos^2 \alpha}$$ At school we had to use this ...
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### Gas viscosity at high pressure, high temperature

EDIT 1 PER COMMENTS I am wanting to model nitrogen gas viscosity as a function of pressure and temperature OR learn of an existing equation that models nitrogen viscosity for the pressure and ...
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### Path of wheels of a bicycle

Why are the wheels of a bicycle moving in concentric circles with the center O? I know that the velocity of the back wheel is parallel to the frame of the bicycle and the velocity of the front wheel ...
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### Gravitational Potential Energy to Kinetic Energy

When a yo-yo is released from a height $h$, the gravitational potential energy is converted to kinetic energy. However, the yo-yo obviously has less acceleration than $g$, $9.8\frac{m}{s}$. This means ...
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### Kinematics problem involving rocket

A rocket is fired vertically and ascends with a constant vertical acceleration of 20 m/s^2 for 1 minute. It's fuel is then all used and it continues as a free particle. Find the Maximum height ...
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Consider a particle of mass $m$ in $6$ dimension. Its coordinate w.r.t. origin $\left(0,0,0,0,0,0\right)$ is given as $\left(x,y,z,\dot{x},\dot{y},\dot{z}\right)$. If we denote $r = ... 1answer 2k views ### What is the difference between negative acceleration and decreasing acceleration? According to Reisnick and Halliday, retardation is the acceleration in the negative direction of time axis ie. opposite to the motion. Decreasing accleretion is the decrease in the magnitude of time ... 1answer 53 views ### If an area remains at temperature 0 Kelvin would the area be frozen in time? If an area is at 0 kelvin, I am guessing that there is no motion. Without motion in an area, will it not look as if time has stopped? 3answers 244 views ### Cart on Ramp with Varying Acceleration For a lab that I have to do, the teacher has given me a data table of the displacement of a cart on a ramp after successive intervals of time. I have used this data to derive the velocities and ... 2answers 2k views ### Finding the optimal angle of a projectile motion [closed] I am trying to solve a task in which I need to calculate the optimal angle($\alpha$) with which the projectile will land the furthest from a height ($h$), so what I basically have is the equations for ... 2answers 1k views ### Projectile Motion Question involving a ball and a ramp inclined at an angle The question is to finde the initial horizontal velocity of the ball at end of the ramp, where it is released. I know how to do this using gravitational potential energy and kinetic energy ... 2answers 569 views ### Why does gravity assist transfer twice the planet's velocity? In orbital mechanics and aerospace engineering a gravitational slingshot (also known as gravity assist manoeuver or swing-by) is the use of the relative movement and gravity of a planet or other ... 1answer 185 views ### helium balloon tied to a car [closed] A helium balloon is tied to the seat of a car. The doors and windows of the car is closed. If the car now starts moving, in which direction will the balloon move- front or back? 1answer 2k views ### Newton 2nd Law: Does vertical force (mass) affect the horizontal acceleration? I learnt before that if 2 forces are perpendicular to each other, they should not affect each other. However in a recent experiment setup (asked in another question): I believe the theoratical ... 1answer 8k views ### Calculation of Distance from measured Acceleration vs Time I have an Accelerometer connected to a device that feeds the instant values of the acceleration in the 3 directions. I've tried to calculate the distance for a vertical movement using these values ... 3answers 167 views ### Looking for the curve traced by a moving bicycle when its steering bar is fully rotated I am looking for a curve traced by a moving bicycle when its steering bar is fully rotated either clockwise or anti-clockwise. How to model it mathematically? Is the curve a circle? My attempt is ... 1answer 628 views ### Gears and efficiency/speed For Christmas me and my brother got an AR Drone, the propellers are on a large gear, which is rotated by a small gear that is connected to the motor. This means the small gear (and therefore the ... 1answer 1k views ### What's the difference between arc length and signed distance? Suppose I give you a position function$x(t)$where t is time and x is position. Then i ask you to find the total distance travelled from$t = 0$to$t = t_f$. Which formula would give you that ... 1answer 145 views ### If a car appears in horison and within 2 seconds passes you by, whats the speed it's doing? While watching the first 4 seconds of driving at 745 km/h is ludicrous from any angle wondered If we knew the curvature of the Earth in a "flat" desert, what would be the speed of the car? ... 2answers 371 views ### Running: Determine how much more energy is needed per extra kilogram of weight (I recently asked this on maths but was directed here) I have recently become a runner and having a keen interest in kinematics I'm very interested in the maths/physics of my running. Can someone ... 1answer 273 views ### Is there a theory about kinetic energy “particles”? [closed] We have a model of electricity which says electrons flow from one place to another. We have a model of optics which says that photons go from one place to another. As I understand, there is currently ... 2answers 42 views ### Motion of an object in a moving car and collison I came across an interesting question today at work. 'Imagine traveling in a car. The passenger has a glass bottle in their hand. In which direction relative to the moving car should the passenger ... 1answer 54 views ### How to sensor Jerk=$d^3{\bf r}/dt^3\$, or higher derivatives (4th, 5th, 6th order) when applied in the equation of motion of a ballistic missile?

Given a 6th order differential equation of motion as usually used in ballastic missile dynamic models. What kind of sensors are usually used to measure Jerk, (or higher order derivatives in ...