# 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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### What's wrong with my solution to this kinematics problem? [closed]

I'm self-studying some kinematics. I'm working on the following problem: You are 9.0 m from the door of your bus, behind the bus, when it pulls away with an acceleration of 1.0 m/s2. You instantly ...
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### Doubt in Kinematics. Help [closed]

Position of a car moving on straight path changing with respect to time as per function, $x(t) = (3t^2 - 2t + 1)m$. Find (a) Initial position of car (b) Distance travelled by car during 10 seconds ...
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### What's wrong with my solution to this basic kinematics problem? [closed]

I'm given the following, pretty basic kinematics problem: A rocket, initially at rest on the ground, accelerates straight upward from rest with constant (net) acceleration $39.2 m/s^2$ . The ...
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### What is the difference between non-uniform velocity and acceleration?

So I know non-uniform velocity as, "Non-uniform velocity is when an object covers unequal distance in equal interval of time in a particular direction or covers equal distance in equal interval ...
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### Trouble with Equations for 2D projectile motion WITH air resistance?

My AP students are learning 2D kinematics, and it got me in the mood to play around with projectiles WITH air resistance, just for fun because we always neglect it, and so that I can maybe show them ...
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### How to find acceleration and deceleration times to reach a certain distance on a frictionless track [closed]

So, I've been having trouble with this for a bit. It seems obvious but I can't find a solution that fits what I'm trying to do. Say you have a car on a track. When you press the accelerator, it starts ...
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### This a question in context to rolling friction [duplicate]

Why is the velocity at the point of contact (between wheel and surface when the condition is rolling without slipping) with respect to the surface remains zero all the times although the center of ...
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### Formula of angular frequency for the metronome pendulum

I am currently doing an experiment with the metronome pendulum (double-weighted pendulum). Since it is a combination of the inverted pendulum and simple pendulum, I am not sure which formula to use to ...
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### Conservation of string equation for two pulley system [closed]

I have a question about writing the conservation of string equation for the system shown below. If the lower pulley moves up, then C increases and A decreases by an equal amount because H is constant....
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### How Would Projectile Motion Be Described in Non-Euclidean Space?

If I and a friend found ourselves in a world described by spherical geometry (as simulated in this linked video https://youtu.be/yY9GAyJtuJ0 ) how would the kinematics equations need to be augmented ...
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### Why is the vibrational kinetic energy of a body ignored when calculating the total kinetic energy?

In calculating the total kinetic energy of a macroscopic rigid body, we add the total translational kinetic energy and the total rotational kinetic energy of the constituent particles. Why is the ...
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### Can anyone help me to do this kinematics problem [closed]

Problem-. Two cars 1 and 2 moves with velocities V1 and V2 respectively.on a road in same direction. When the cars are separated by a distance d,the driver of car 1 applies brake and the car moves ...
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### Why is it said that speed always remains constant in circular motion?

One can cover circular motion with different speeds at different positions, right? The only aim is to complete his circular motion, right?
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### Turning a wheel of a car, stationary vs turning

At the end of class, my physics professor left us with a question: "Why turning the wheel of a static car is much harder than turning one in motion?" I took the wheel to be a little wide ...
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### Calculating maximum positive displacement [closed]

The velocity of a particle is given as $\vec{𝑣}(𝑥)=( 6𝑥−5𝑥^2) \hat{i}$. How long does it take for the particle to reach maximum positive displacement? I figured that max positive displacement ...
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### Prove the motion equation of a particle in a central force field [closed]

Prove that $a=v\frac{dv}{d\rho}$ where $a$ is acceleration(scalar) of a particle moving in a plane and $v$ representates the velocity(scalar), if $\vec{a}$ always pass through a fixed point O. To ...
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### Incorrect Equations of motion? Rotating Table with Driving Mechanism

This problem is an example in Lagrangian Dynamics by Wells. $\textbf{Example 3.6}$ (p. 48) $\hspace{.5cm}$The rotating table D has an angular velocity $\dot{\alpha}$ determined by the motor $M_1$. ...
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### Why can gravitational acceleration not be detected by experiments

I was doing research into how $G$ forces are calculated, and I was told that they show all acceleration that can be "sensed" by humans (i.e. all non-gravitational acceleration). This ...
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### Linearity in acceleration in kinematics (Intro to Physics)

I am a student in an Introduction to Physics class, and I have the following question which I am confused about, and how two parts of the answers relate to each other. (We are doing 1d kinematics) A ...
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### In what direction does a static electron moves in presence of plane electromagnetic wave?

Consider that we have the electric field, $$\mathbf{E}=E_0\cos(kz-\omega t)\hat{\mathbf{x}}\tag{1}$$ and the magnetic field, $$\mathbf{B}=\frac{B_0}{c} \cos(kz-\omega t)\hat{\mathbf{y}}\tag{2}$$ These ...
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### Intersection point from acceleration [closed]

Two objects facing each other over a distance of 88m start moving from rest at an acceleration of 0.3m/s^2 and 0.2m/s^2 respectively, after how long do they intersect? I've tried everything to find ...
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### A question on position and velocity vectors from a vector space perspective

In introductory physics we are taught about position and velocity vectors. Though the representation of those vectors is identical (i.e. $x\hat{x}+y\hat{y}+z\hat{z}$) they must belong to separate ...
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### Homework problem motion question [closed]

A ball is accelerated at an angle of 30° from vertical by a spring at a rate of 30m/s^2 for 0.5m. Using g=10m/s^2 and assuming the ball leaves the spring at y=0, How far does the ball travel before ...
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### How to create a position-vs-time graph from this?

I'm given the following problem: At what times is the particle found at $x= 20m$? I know this is a very fundamental problem, but still I cannot see how the answer ends up being $4$ and $12$. Note ...
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### Mass acceleration by spring, including friction [closed]

A simple problem that's giving me headaches. A block being pushed by a preloaded spring, what is the speed when the spring fully extends? $k$ is spring stiffness in $N/m$, $x$ is preload distance of ...
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### Relative motions, between inertial and non-inertial frames or bodies

I had no other way to put my problem to you guys thus I am taking an example.... Here, ...
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### How do we define $G$s?

I am going to explain what I think I know and how that leads up to my question - please correct any false claims I make or conclusions I draw. I initially thought that $G$s were defined purely by ...
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### Polar radius and position vector: two-dimensional kinematics for high school students

We consider for example this image, which is a polar graph of a naval unit's on-board instrumentation with vector radius (or polar radius) $\rho$ and anomaly $\theta$ or polar angle. We know that a ...
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### What would the parametric equations be for an object moving along a 2D curve at a constant speed?

Please excuse my ignorance or poorly worded question (this is my first one), but I am wondering how to go about deriving the parametric equations for the x and y motion of an object traveling along a ...
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### Force and Velocity directions

When ever the force and velocity are in thesame direction(0°), an object speeds up. When ever the force and velocity are in opposite directions(180°), the object slows down. Also , when ever force ...
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### Difference between horizontal and oblique projectile motion

I have been studying kinematics and I am stuck with understanding what is oblique projectile and what is horizontal projectile and what is the difference between them? Can someone please explain them ...
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### Direction of displacement

Displacement is defined as the vector obtained by joining the final position to the initial position (head towards the final position). Well,i know this is silly but what are these final and initial ...
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### Acceleration function of position and time

I have an acceleration function in python with position and time parameters and returns the acceleration value. I need the end velocity at a position ,start velocity is zero. how to calculate this ...
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### Kinematic formulas for constant $n$th derivative of position

I was wondering how to solve for $x(t)$ in the general case of constant $n$th derivative of $x$. This means to solve the equation $$\frac{\mathrm{d}^n x}{\mathrm{d} t^n}=q,$$ where $q$ is a constant. ...
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Exploring the benefits of deadblow hammer physics in sports. I play badminton, and have developed elbow pain that is aggravated whenever I smash (overhead forehand, like a tennis serve). This is ...
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### Kinematics: rest and motion [closed]

A ball is dropped from a height of 19.6 m above the ground. It rebounds from the ground and raises itself up to the same height. Take the starting point is the origin and vertically downward as the ...
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### Rate of change of the position with respect to the distance

In my textbook, there is a theorem which states that if the position vector of a body is $\overrightarrow r$ and the covered distance is $s$ such that $\overrightarrow r$ is a function of $s$ then \...