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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126 views

Projectile's angle in midflight

For a missile travelling from (0,0) at angle $\theta$ (to the horizontal) and initial velocity $u$, the y (vertical) position at time t is given by $s_{y} = u\sin (\theta) t - 0.5gt^{2}$ and the x ...
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1answer
417 views

Circular motion and centrifugal force

Assuming a race car drives around in a circle of radius r, center (0,0), linear velocity v, and ignoring centrifugal forces and friction I can calculate the position at any time, t. Angular velocity ...
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2answers
330 views

Best shape to reduce the splash of a droplet?

Our coffee machine catches the last couple of droplets, after your cup is removed on a shape to reduce plash of the coffee droplets. These shapes are placed inside the spill reservoir. The shape ...
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1answer
382 views

Kinematics question [closed]

An electric train accelerates uniformly from rest to a speed of 20m/s which it maintains until the brakes are applied. It is then brought to rest by a uniform retardation equal in magnitude to twice ...
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3answers
1k views

Getting position from an accelerometer on an Android phone

I know that integrating acceleration twice will give me position (acceleration-->velocity-->position) but how can I do all this when I all I have are a set of data points (ex: 1 second = some # ...
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2answers
1k views

Do you use the magnitude equation to get speed from an accelerometer?

A guy suggested to me that getting speed from an accelerometer required the use of this equation: $\text{speed} = \sqrt{x^2 + y^2 + z^2}$ This does not make any sense to me, all that you would get ...
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3answers
158 views

Doubt in Kinematics

I know that this isn't the place for such basic questions, but I didn't find the answer to this anywhere else. It's pretty simple: some particle moves in straight line under constant acceleration from ...
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1answer
321 views

Relativistic kinematics of particle decay

Suppose a particle decays to three other particles. The masses of all particles are assumed to be known and we work in the rest frame of the parent particle. So there are 12 parameters for this ...
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1answer
3k views

Calculate displacement in position from knowing constant acceleration

I have recently started studying physics at school, and my teacher went over the following equation without explaining about it too much: $$d~=~vt+\frac{1}{2}a t^2.$$ I have wondered, why would this ...
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0answers
467 views

What is the initial velocity of a projectile so that it passes through a target point in its trajectory? [closed]

Let's say I have a projectile being thrown by a player in my 2-D game. I want to work backwards and find the initial velocity to apply to the projectile such that it passes through a target point in ...
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0answers
219 views

Getting pairs of angle and velocity for a projectile to a given destination

I'm trying to calculate the initial velocity $v_0$ and angle $\theta$ for a given destination $(x, y)$ with a launch height of $y_0$. Obviously there will be a set of pairs of velocity and angle that ...
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1answer
844 views

Experiment to measure initial speed of high speed tennis ball?

I want to devise a way to measure the initial speed of a tennis ball fired from a tennis ball cannon, but without using any speed-measuring devices. Just plan distance-measuring and physics formulas. ...
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1answer
207 views

Shooting a bullet at a system of blocks [closed]

So, I made this question up myself.... and I'm curious about the answer. It requires only secondary-school-level knowledge of physics: You have a surface (ground) with a certain coefficient of ...
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2answers
3k views

Galilean invariance of the Schrodinger equation

I am only asking this question so that I can write an answer myself with the content found here: http://en.wikipedia.org/wiki/User:Likebox/Schrodinger#Galilean_invariance and here: ...
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2answers
7k views

Calculating Average Velocity

I understand that the concept of an average of a data list means finding a certain value 'x', which ensures that the sum of the deviations of the numbers on the left of 'x' and on the right of 'x' ...
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2answers
3k views

How can I add an acceleration vector to a velocity with a different direction?

I am in my last year of high school and am struggling with some homework. I'm sorry if this question is incredibly stupid, but I simply can't find the answer in my notes. If I have an object with a ...
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2answers
250 views

Equation of motion for average acceleration

I am trying to solve the following: A man of mass 83 kg jumps down to a concrete patio from a window ledge only 0.48 m above the ground. He neglects to bend his knees on landing, so that his ...
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3answers
256 views

If an electric car were to drive without having to stop, would the range be greatly affected by the speed at which the vehicle is moving?

Of course aerodynamics factors into this question, and the faster you are moving the more air you have to push out of your way, the more energy you use. But would the difference be only a small ...
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3answers
638 views

Speed of an object in air versus in vacuum

Okay, imagine that you are shooting a rocket down a tunnel that is 60 miles long and the rocket is travelling at 60mph, so the rocket should reach the end of the tunnel in a hour, right? Yep, in an ...
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1answer
143 views

How to track the visual path of a LEO satellite as seen from the ground

I have been struggling with this problem for a while so I decided to ask. I'm new here and I'm not sure where this type of question belongs, so forgive me if this isn't the right section. I am ...
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0answers
214 views

I need help with the following Physics' questions [closed]

I need to know which formulas and the step-by-step answers for the following physics questions: 1. You throw a ball upward with an initial speed of 7.0 m/s, and it returns to your hand o.92 ...
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0answers
146 views

A 0.1kg ball of dough is thrown up with a velocity of 15m/s. What is the momentum halfway up? [closed]

I know that $p=mv$ and (0.1kg)(15m/s)=1.5 kg m/s and the momentum at the vertex is 0, but what is the momentum halfway up?
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3answers
295 views

When can one write $a=v \cdot dv/dx$?

Referring to unidimensional motion, it is obvious that it doesn't always make sense to write the speed as a function of position. Seems to me that this is a necessary condition to derive formulas ...
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1answer
374 views

How deep is the well, given this data?

A rock is dropped into a well. A timer starts when the rock is dropped and is stopped when the noise of the rock hitting the ground of the well is heard. How deep is the well? Here's what I have so ...
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3answers
2k views

Why isn't average speed equal to displacement over time?

I'm in an introductory Physics course and I need help! During a one-hour trip, a small boat travels 80.0km north and then travels 60.0km east. What is the boat's average speed during the one-hour ...
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0answers
70 views

How to calculate the correct coordinates from a distorted video of a projectile?

I am working on a high school project that is related to projectile motion. I am exploring how exactly the position of the center of mass affects the trajectory of a long but thin, javelin-like ...
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1answer
704 views

Newton first law of motion, braking suddenly in car

While driving down the road, if you hit the brakes suddenly, your body moves forward. Explain the reason for this.
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2answers
2k views

3D: Get linear velocity from position and angular velocity

I want to find out the linear velocity of a point in 3D space, (Euclidean), given: Its position Its angular velocity The point it's rotating around (fulcrum) (This is a problem I need to solve ...
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2answers
374 views
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3answers
637 views

Projectile motion, canon vs cliff

A cannon is placed at the bottom of a cliff 85 m high. If the cannon is fired straight upward, the cannonball just the reaches the top of the cliff. a) Calculate the initial speed of the cannonball. ...
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1answer
137 views

Is it necessary to know initial y velocity to solve this projectile motion problem?

A marble is launched horizontally off a 93.0-cm high table causing the marble to land on the floor 1.85 m from the base of the table. a.) How long was the ball in the air? b.) With what ...
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1answer
652 views

Projectile motion problem with upward acceleration and horizontal velocity [closed]

An electron in a cathode-ray tube is traveling horizontally at 2.10×10^9 cm/s when deflection plates give it an upward acceleration of 5.30×10^17 cm/s^2 . B.) What is its vertical displacement during ...
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1answer
154 views

What's the difference between these two formulas and how are these called?

I just want to know the differences between these two formulas: $h = h_0 + v_0 t ± \frac{1}{2} g t^2$ and $y = y_0 + v_{0y} t + \frac{1}{2} g t^2$ Also, how are these called in English?
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3answers
1k views

In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?

In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent? This question is referring to the concept of projectile motions.
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2answers
443 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 ...
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2answers
170 views

London into Australia in 90 minutes

Me and my friend are having a debate on whether it would be possible for a human to travel at 15,000 miles an hour from London to Australia in the matter of 90 minutes. Would a human be able to ...
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2answers
617 views

Monkey and tree - projectile motion

The famous scenario: A hunter is trying to shoot a Monkey hanging from a tree. However, this question doesn't mention the monkey jumping down from the tree or trying to escape. (The hunter uses a ...
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1answer
2k views

How do I find the magnitude and angle of the velocity?

I'm confused about the following problem. A ball is shot from the ground into the air. At a height of $9.1\text{ m}$, its velocity is $v = (7.6\hat{\imath}+ 6.1\hat{\jmath})\text{m/s}$, with ...
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0answers
26 views

Movement of a ball on a curved ramp [duplicate]

Possible Duplicate: What is a natural movement of a ball on a upward curve (the two arrow lines pointing upward) given no external force? http://i47.tinypic.com/mt55s7.jpg -See for image ...
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2answers
680 views

What is a natural movement of a ball on a upward curve (the two arrow lines pointing upward) given no external force?

If you drop a ball down a upward curving parabolic ramp, what is the expected movement of the ball? Assume the ball is set into motion with no external force. Would it go all the way from point A to ...
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4answers
2k views

How to brake 'beautifully'?

Sometimes when I'm driving my car, I play a "game" against myself in which I try to minimize the deceleration felt by passengers (including myself) while still braking in a reasonable short space. I ...
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1answer
427 views

Projectile motion in two and three dimensions question?

So I bought this book in the library and physics fascinates me and I found this quote in the book " Galileo has proved that when any effects due to air resistance are ignored, the ranges for ...
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2answers
182 views

Non-zero higher time derivatives of position?

My mom told me to use speed control, which would allow the car to remain at constant speed. I told her that its impossible for a car to maintain constant speed, as slight changes in friction on the ...
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5answers
2k views

How a spacecraft travelling near light speed avoid asteroids?

How would a spacecraft traveling near light speed avoid a (relatively dense group of) asteroids? Or suppose such spacecraft is designed, how would the physics work for steering it inside such a ...
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2answers
401 views

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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3answers
945 views

Calculating vertical velocity component of a particle with mass, given the hit point of parabolic motion

Consider the following situation: I have a particle with a given mass that at a given instant of time (let's say $t_{0}$) is placed at the system origin. The particle has a constant velocity ...
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1answer
754 views

Non-commutative property of rotation

Addition of angles are non-commutative in three dimensions. Hence some other angular vector quantities like angular velocity, momentum become non-commutative. What is the physical significance of this ...
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1answer
3k views

Why is the velocity on the top of a wheel twice the velocity of its axle?

When a wheel is rolling, not skidding, and its axle moves at velocity $\vec{v}$, then a point on the top of its circumference will move at velocity $2\vec{v}$, shown below. I really don't ...
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2answers
4k views

Why do cars gain lift while going at a high speed?

I've been researching the physics involved with spoilers and I've just been turning up the same information about spoilers giving the back wheels of a car more traction by acting as an up side down ...
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1answer
262 views

Is it possible to determine particles' velocities from their crossings on a ring?

2 particles are constrained to move in a ring. Both particles begin moving at $t=0$ from $p=0$, each particle moving in the opposite direction of the other. It is known that they are moving at ...