The velocity tag has no wiki summary.
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How to deduce the theorem of addition of velocities?
Lorentz contraction and time dilatation can be deduced without Lorentz transformation. Can you deduce also the theorem of addition of velocities
$$w~=~\dfrac{u+v}{1+uv/c^2}$$
without Lorentz ...
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2answers
316 views
At what point does a projectile leave a slingshot?
Assuming a frictionless / "perfect" environment, and given a ball held in an elastic sling (like a hand-held catapult) where the pocket is lighter than the projectile itself, what is the point at ...
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1answer
182 views
Tricky Conservation of Momentum problem: find the ratio of the carts by mass percentage lost [closed]
A wagon is coasting at a speed $v_A$ along a straight and level road. When 42.5% of the wagon's mass is thrown off the wagon, parallel to the ground and in the forward direction, the wagon is brought ...
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2answers
465 views
What will be the relative speed of the fly? [duplicate]
It has happened many times and i have ignored it everytime.
Yesterday it happened again .
I was travelling in a train and saw a fly (insect) flying near my seat.
Train was running at a speed of ...
1
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2answers
368 views
Sign of Velocity for a Falling Object
I'm working on a homework problem in Mathematica. We have to graph the height and the velocity of a function given an initial height and initial velocity. However, when I do the graph for the velocity ...
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3answers
251 views
Train crash: are these situations alike?
I was just wondering... I believe that if a car travelling 50 miles per hour crashes into a wall, the result should be the same as crashing to another car also travelling 50 miles per hour (but in the ...
3
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2answers
164 views
Air velocity in a double-skin facade
I was wondering how the air flows in a double skin facade? Say I have a glass facade with a depth of 1m, a height of 200m and a width of 10m. It is a single vertical shaft all the way up with openings ...
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1answer
3k views
How to find maximum velocity
I stack a question about projectile question.
The question was
A projectile is being launched from ground level with no air resistance. You want to avoid having it enter a temperature inversion ...
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2answers
1k views
How to find minimum velocity without time? [closed]
I have a physics problem that says
A 76.0-kg boulder is rolling horizontally at the top of a vertical cliff that is 20m above the surface of a lake. The top of the vertical face of a dam is ...
0
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2answers
331 views
How to compute drag coefficient given initial position, initial velocity and final resting position?
The equations I'm using are:
x = x + (DT * vx)
vx = vx * C
My DT is always 0.01 and the coefficient C (related to a linear ...
2
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3answers
784 views
What is the velocity area method for estimating the flow of water?
Can anyone explain to me what the Velocity Area method for measuring river or water flow is?
My guess is that the product of the cross sectional area and the velocity of water flowing in a pipe is ...
0
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1answer
227 views
Finding The Resultant Vector [closed]
A plane is flying southeast at 215 km/h. Suddenly there is a wind from the north at 75 km/h. What is the plane's new velocity with respect to the ground in standard position?
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2answers
177 views
Horizontal Speed of Descending Parachute
I understand how to get the vertical (descent speed) of a parachute and its payload, but how could one find the horizontal speed/velocity of this parachute depending on the speed of the wind? (yeah I ...
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3answers
297 views
Numerical simulation of mechanics problem
Say I have a planet and shoot something with a given velocity, which is a significant portion of the escape velocity, in a given angle into the sky. It has some initial velocity and there is the force ...
2
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1answer
165 views
Motion is relative, right? And most pop sci relativity explanations are somewhat incorrect?
On page 20 of A Brief History of Time:
. . . all observers should measure the same speed of light, no matter
how fast they are moving.
But in an observer's frame of reference, they're actually ...
2
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4answers
217 views
Are circularly defined {velocity, distance, and time} a problem in physics?
In order to measure velocity, one needs a calibrated measuring stick and clock. But in order to calibrate a measuring stick you need a calibrated clock and velocity. And in order to calibrate a clock ...
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2answers
149 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 ...
3
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3answers
865 views
Is it possible to calculate weight of person with sensors found in today's smartphone?
Is it possible to calculate the weight of a person by only
using his smartphone, some action he must perform (jump, rotate etc.) and
some data like his height or age.
Current smartphones have the ...
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0answers
82 views
Physics behind 2 different wall kicks
I'm looking at a situation where a sprinter starts at some distance x from a wall. The goal is to sprint to the wall, hit it, and get back to the start as quickly as possible. There are two ways ...
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2answers
361 views
Is instantaneous velocity an abstraction?
In introductory analysis, the discussion the derivative emphasizes that while average rates of change are measurable, instantaneous rates of change are a "limiting abstraction". While this makes ...
0
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1answer
530 views
Simple Harmonic Motion Question [closed]
I have two formulae:
Displacement = Amplitude * Cos(Angular Frequency * Time)
Velocity = - Amplitude * Angular Frequency * Sin(Angular Frequency * Time)
OR
$x = Acos(wt)$
$v = -A.w.sin(wt)$
And ...
1
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1answer
156 views
Measuring a Rod in Motion with two Synchronized Clocks
An explanation of special relativity I'm struggling with, goes like this:
A rod traveling by a "stationary" observer has its length measured by use of two stationary synchronized clocks (synchronized ...
2
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1answer
313 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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1answer
200 views
Calculating vector of plane resulting from tailwind
In some basic physics homework I have, it asks what the resulting vector would be for a plane traveling at x m/s in y direction that is affected by a tailwind going in z direction at w m/s. How would ...
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2answers
3k views
What is the difference between angular speed and tangential speed in a circular motion?
I was looking a long time for the way the equations of this two speeds are obtained, and i found pretty much nothing important, so can someone explain how are those obtained, and which is the ...
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1answer
650 views
Sound velocity in water
Conductivity, temperature, depth sensors are used by oceanography to calculate the velocity of sound at varying depths.
These measurment values are used to comprise sound velocity profiles like the ...
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0answers
155 views
If you make a steel rod from here to Alpha Centauri and move it, will the movement appear there instantly? [duplicate]
Possible Duplicate:
Is it possible for information to be transmitted faster than light?
imagine this theoretical situation:
You have make an extremely long piece of steel (or anything ...
11
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2answers
449 views
What is the terminal velocity for a mobile phone
You may have seen the story of the iPhone which was dropped from perhaps 13,500 feet by a skydiver - it survived.
This made me wonder how to work out the terminal velocity for something like that. ...
2
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1answer
226 views
whats the rate of energy increase required for constant acceleration between 0.0c and 0.99c?
I was wondering how much energy would be required to accelerate 1000kg to 0.99c at 1G.
What I don't understand is what the rate of increase of energy is required as velocity increases. I was looking ...
1
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1answer
233 views
If someone shoots a gun (45 caliber) at someone holding up a table or desk 10 feet away, does it slow or turn the bullet away?
Assume it's a standard .45 caliber handgun. Shooter is 10 feet away, and we hold a desk, mini-table, blackboard, etc on our chests(to protect vitals).
How do you figure out the bullet's decrease in ...
1
vote
3answers
4k 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 ...
1
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1answer
133 views
Is it theoretically possible for the orientation angle of a projectile to remain exactly equal to the orientation of velocity?
This question is sparked by my answer to this question: Is this simulation following real physics?
After examining the math, I don't see how it is theoretically possible for the situation simulated ...
3
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1answer
837 views
what is uniform velocity?
i have a very basic question from school days. what does it mean to say an object is moving with uniform speed? it seems to me now that it should be an unit dependent concept.
for example if speed is ...
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4answers
753 views
Double light speed
Let's say we have 2 participles facing each other and traveling at speed of light
Let's say I'm sitting on #1 participle so in my point of view #2 participle's speed is c+c=2c, double light speed? ...
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2answers
165 views
Thought experiment that seems to involve something growing at twice the speed of light. Is anything wrong?
Let foo be some unit of distance and bar be some unit of time which have been chosen so that the speed of light c = 1 foo/bar. Position several observers along a line each separated by one foo, and ...
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3answers
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Terminal Velocity
Let Suppose a bullet of 2 gram is falling with the speed of 200km/h.
Now how can we know the time after which it gains it terminal velocity.
Also when it gain its terminal velocity the force of ...
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3answers
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Seeing light travelling at the speed of light
Imagine there are two cars travelling "straight" at the speed of light*, $A$, and $B$. $B$ is following directly behind $A$.
Suddenly, $B$ switches on its headlights. Will $A$ be able to see this ...
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6answers
422 views
How low can an electron go?
Title says it all - recently I encountered a strange homework exercise on de Broglie dual theory with an electron wavelength of few millimeters - which implies the velocity lower than 1 m/s. I ...
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3answers
242 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 ...
5
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2answers
781 views
Escape Velocity of Asteriod 243 Ida
I was reading about this asteroid (apparently, it has a moon, isn't that awesome?) and I started thinking about if I was on this asteroid, and I jumped, would I fall off?
It's been a while since I ...
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2answers
214 views
What does this observation of instantaneous velocity in Brownian particles mean?
I read this artice: Physicists Prove Einstein Wrong with Observation of Instantaneous Velocity in Brownian Particles
“We’ve now observed the instantaneous
velocity of a Brownian particle,” says
...
5
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4answers
656 views
A Basic Question about Gravity, Inertia or Momentum or something along those lines
Why is it that if I'm sitting on a seat on a bus or train and its moving quite fast, I am able to throw something in the air and easily catch it? Why is it that I haven't moved 'past' the thing during ...
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2answers
466 views
Velocity of Voyager 1
I was reading Wikipedia which stated
....Voyager 1's current relative velocity is 17.062 km/s, or 61,452 kilometres per hour (38,185 mph).....
It travels away from sun. So sun's gravity must ...
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1answer
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Find velocity and displacement from force equation
How to find velocity and displacement equations from a given force equation? For instance, it was given the following 1-D equation:
$$F = b_1(v_1-v) - b_2 v$$
$v_1$, $b_1$ and $b_2$ are constants.
...
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3answers
2k views
How do you find the velocity function of a mechanical wave?
With the form $y(x,t)=A\sin(kx-\omega t+\phi_0)$, there are two variables, How do I find the velocity? I don't know I can apply derivative with two variables.
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4answers
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How fast is earth moving through the universe
As the galaxy is moving and the solar system orbiting the galaxy and the Earth orbiting the sun. So how fast is each object moving and what is the fastest we move at?
Do we even know how fast the ...
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2answers
332 views
Determining Maximum Velocity of an object traveling horizontally
I'm in the process of working on a physics related game. I'm looking to find the maximum velocity of an object given it's mass and the force acting on it when it is traveling horizontally. I believe ...
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2answers
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Mass of particle near light speed in a medium
I am trying to get a common understanding from these two previous questions:
Why does the mass of an object increase when its speed approaches that of light?
What happens if light/particles exceeded ...
3
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2answers
334 views
How much does it cost every time your car stops for a traffic light?
Every time we have to stop the car, it is costing us extra money, because we have to then accelerate to full speed again. I would like to know how much.
In order to simplify the situation, we can ...
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3answers
837 views
What is terminal velocity?
What is terminal velocity? I've heard the term especially when the Discovery Channel is covering something about sky diving. Also, it is commonly known that HALO (Hi-Altitude, Lo-Opening) infantry ...
