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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3
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2answers
413 views

The Double Integrator: Matching velocity and position as quickly as possible with only a limited amount of force available

If a body with mass $m$ begins at position $x_0$ with velocity $v_0$ and experiences a force that varies as a function of time $f(t)$ (and we ignore gravity, friction, and everything else that might ...
7
votes
5answers
880 views

Should you run when under rain?

When it's raining, would you get less wet if you run or more wet? I think you will get less wet, because rain is coming down in a constant volume and if you run you will have a shorter amount of time ...
2
votes
2answers
678 views

How to calculate a firing location from point of impact data?

I would like to know how to calculate the point at which a bullet is fired from a gun given information from the scene where the bullet falls. The scene would contain the point of impact (GPS ...
0
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2answers
6k views

What do I need to do to find the stopping time of a decelerating car? [closed]

The question is: A car can be stopped from initial velocity 84 km/h to rest in 55 meters. Assuming constant acceleration, find the stopping time. Sorry for my ignorance, but I need to review ...
0
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2answers
469 views

Why wouldn't this system of equations determine where two balls meet?

A ball is thrown vertically upwards at $5\text{ m/s}$ from a roof top of $100\text{ m}$. The ball B is thrown down from the same point $2\text{ s}$ later at $20\text{ m/s}$. Where and when will ...
1
vote
1answer
631 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 ...
0
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1answer
181 views

I think I disprove this with kinematics, but energy says it is right

! Here is my kinematics argument. For now I am only going to look at ball 2 and ball 3. Make note of the following data. $|v_0| = 10m/s$, $y_0 = 10m$, $\theta_2^0 = 30^0$, $\theta_3^0 = -45^0, g = ...
2
votes
1answer
125 views

If 2 bodies are moving at equal speed parallel, and one throws something at a right angle to itself, will the thing thrown hit the other body?

Me and some friends were discussing the idea of (in a perfect scenario, no air resistance or gravity to affect the results) 2 bodies moving in the same direction exactly parallel to each other. If ...
1
vote
2answers
574 views

2d simulation shooting projectiles that inherit the gun's veocity at a moving target while also moving

Overview: I'm working on programming a simulation that requires 'shooting' projectile-type objects at other moving objects. How can I calculate the angle at which to shoot the object to hit? Details: ...
1
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2answers
331 views

Using acceleration to plot position

Sorry if this question is dumb, and I know is physics 101, but I'm not that good with physics. I'm writing an iPhone program that by collecting the acceleration data of the device tries to replicate ...
2
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8answers
2k views

Real world examples for projectile thrown upwards or downwards

I am preparing a physics course for high school about projectile motions. If a projectile moves with initial velocity $v_0$ in the gravitational field of the earth, the equation $$ s(t) = 1/2 g t^2 ...
0
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2answers
462 views

How to calculate total distance and time a puck will move?

To simulate a puck's movement, I use the following model (please restrain from discussing the model, it makes the simulation look the way I want it to) and would like to know how to calculate the ...
0
votes
2answers
762 views

Basic Free Fall Problem [closed]

So I am trying to remember my childhood doing some Physics problems, but seems that I forgot almost everything. But it's not a big thing... that's why I'm training! My problem is pretty basic ...
1
vote
0answers
259 views

How to model an accelerometer measurements on a car wheel?

I am working on kinematically modelling an accelerometer on a car wheel. When working on the initial conditions, I am confused whether or not I should use the gravitational acceleration since there ...
1
vote
2answers
240 views

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 ...
0
votes
1answer
306 views

Is spherical coordinates enough to calculate the exact position of a point with rotations included?

With "Geographic coordinate system" we only get the location, no rotations or anything. Translated into latitude and longitude. Where with "Spherical coordinate system", we should be able to get the ...
1
vote
0answers
107 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 1)If we knew the curvature of the earth in a "flat" desert, what would be the speed of the car? ...
0
votes
1answer
156 views

Find the acceleration based on V² x d graph

How could I find the acceleration of a body knowing only that its position and velocity satisfy $v^2 = f(x)$, where $f(x)$ is a known function of $x$ (position)?
0
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1answer
693 views

Projectile motion question: vertical and horizontal graph

I've have got some vertical and horizontal distances for a projectile-like motion. In order to work out the trajectory, why is it better to plot on the x-axis, "horizontal distance^2", and on the y ...
8
votes
4answers
770 views

Why does a ping pong ball change direction when I spin it on a table?

When I spin a ping pong ball on the table, it rolls forward in the opposite direction of the spin, and then eventually changes direction and rolls backward. Here's a video demonstrating the effect. ...
7
votes
1answer
358 views

what is the kinematics of a particle with complex mass?

particles with real-mass have time-like kinematics ($ds^2 > 0$). particles with zero-mass have light-like kinematics ($ds^2 = 0$). particles with imaginary-mass have space-like kinematics ($ds^2 < ...
5
votes
2answers
11k views

Difference between momentum and kinetic energy

From a mathematical point of view it seems to be clear what's the difference between momentum and $mv$ and kinetic energy $\frac{1}{2} m v^2$. Now my problem is the following: Suppose you want to ...
7
votes
5answers
15k views

How to get distance when acceleration is not constant?

I have a background in calculus but don't really know anything about physics. Forgive me if this is a really basic question. The equation for distance of an accelerating object with constant ...
0
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3answers
1k views

Very basic question: When to use $s=vt$, $s=1/2vt$, $s=at$ and $s=a/t^2$?

Very basic question: When to use $s=vt$, $s=\frac{1}{2}vt$, $s=at$ and $s=\frac{a}{t^2}$? What was the difference between those?
2
votes
1answer
479 views

Concept of relative speed

I am traveling on a train running at a speed of 100mph. If from the train I shoot a ball at a speed of 100mph in opposite direction then what would be the speed of the ball with respect to a person ...
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0answers
226 views

How to calculate the resulting velocitys and rotation speed after two concave polygons collide in 2d

so I've been searching google for how to do this, but all anyone seems to care about is collision detection =p, and no results come close to teaching me how to calculate 2d elastic collision between ...
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0answers
349 views

Understanding 1D Kinematics and Uniform Acceleration? [closed]

So I was given the following homework problem: You land on an unknown planet somewhere in the universe that clearly has weaker gravity than Earth. To measure g on this planet you do the following ...
9
votes
4answers
3k views

Can superconducting magnets fly (or repel the earth's core)?

If a superconducting magnet and appropriate power supply had just enough $I\cdot s$ (current $\cdot$ length) so that when it was perpendicular to the earth's magnetic field, the force of the ...
7
votes
2answers
1k views

Should acceleration be included in state vector of a Kalman filter?

I'm developing (actually adopting existing solution) a Kalman filter to model motion of a vehicle (UAV or automobile). The state vector will include position, velocity, and, possibly, acceleration. ...
2
votes
2answers
365 views

“Observed” angular velocity

I have a homework question based on the following diagram: I need to find the angular velocity of the object as seen by an observer at the origin of the frame. The question says that the observed ...
3
votes
6answers
5k views

Ion Drive Propulsion Top Speed

I would like to know if there is some formula / graph which would provide / show the efficiency of a certain type of propeller in space. Specifically, I'm interested in the acceleration attainable at ...
1
vote
3answers
8k views

Find radius of curvature, given a velocity vector and acceleration magnitude?

The particle P moves along a space curve. At one instant it has velocity $v = (4i-2j-k)$ $m/s$. The magnitude of the acceleration is 8 $m/s^2$. The angle between the acceleration and the velocity ...
2
votes
1answer
626 views

Circular equation of motion

I'm reading an article which describes a generation of artificial AKG signal. The article states that they use the following equation of motion: $ \left \lbrace \begin{array} {ccc} \dot x &=& ...
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vote
2answers
275 views

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 ...
1
vote
2answers
2k views

Ascent rate and size of balloon

I am part of a school project, Project Stratos to send a balloon to the edge of space (the closer side :P) and was wondering how you would work out the accent rate of a large balloon (roughly 1m^3 of ...
1
vote
2answers
286 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 ...
0
votes
2answers
308 views

In a 2D problem with a thrown object, why is the acceleration along the x-axis equal to 0?

I'm starting Physics, and I don't understand why the acceleration along the x-axis is zero for an object thrown near the surface of the Earth. This may be problem specific, but I wouldn't know since I ...
0
votes
2answers
1k views

Can someone explain the physics of a standing jump?

I would like to use something like a kinematic equation to know where the person will be in the jump at a given time. However since I think acceleration is not constant because of the jump force it ...
3
votes
2answers
1k views

Formulas for ball rolling in a bowl?

I'm developing a program where I've a ball/sphere rolling in a bowl from the side at top, till the center at bottom, and I'm trying to get the formulas for: The rotation angle and the position of ...
0
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2answers
2k views

Position in circular motion

Is it possible to determine the position of a particle undergoing circular motion, in x-y coordinates, at any given time and velocity? I'm thinking it has something to do with $\pi$
2
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1answer
196 views

Is it possible to rotate an angle on perfectly smooth ice?

You must start and end with the same pose. Prove it if you think you can't.
8
votes
4answers
22k views

What is the relationship between kinetic energy and momentum?

I can't seem to figure out the relationship between $E_k$ and $p$ or $F$. I understand that the units are pretty different. But for example: A bullet with a mass of 10.0g is moving at the speed of ...
-1
votes
3answers
324 views

Help getting the distance an object has moved

What is a distance an object went through at the speed of 14hm/min for 6 hours? I am having problems with conversions. First, I tried passing 14hm/min to m/s. I did it alright. But now I am unsure. ...
7
votes
4answers
617 views

What's my weight when jumping on a bicycle from a higher to a lower ground?

Before I start defining the situation and asking a question, I'd like to make a few things clear: this is not a homework, merely a matter of personal interest and enthusiasm I am neither a ...
0
votes
3answers
296 views

Deccelerate and Accelerate to achieve timed journey

I have a vehicle traveling at initial speed $100\:\mathrm{m/s}$. Expected destination speed is also $100\:\mathrm{m/s}$. Maximum deceleration is $3$. Maximum acceleration is $10$. Distance to the ...
2
votes
4answers
5k views

How to calculate displacement of an object [closed]

I am having a little bit of trouble with this following problem - Suppose a particle has initial velocity and is moving with a constant acceleration. After t seconds its velocity is v. What will its ...
3
votes
2answers
373 views

Is the speed of a person falling down different if doing a forward somersault during the fall?

Let's imagine this in an situation where a person jumps down from a smaller building, a garage for example. The exact numbers aren't really important here, since I'm not aiming for an exact answer, ...
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votes
2answers
1k views

Rigid body dynamics joints

I can't seem to find any info on connected rigid bodies by a joint. Can someone explain the basics to me? I'm trying to do a little research to find out how feasible it would be to implement 3d ...
7
votes
2answers
1k views

Physics of simple collisions

I'm building a physics simulator for a graphics course, and so far I have it implementing gravitational and Coulomb forces. I want to add collisions next, but I'm not exactly sure how to go about ...
1
vote
7answers
6k views

I need help with finding distance traveled

How do I find the distance traveled of an object if the speed is not constant?