The time rate of change of the position of an object

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What is the pressure in a vertical pipe that has moving fluid through it?

I have a system like this When the valve is closed, pressure along any point along the thin tube may be found thru pgh. 1. What about when the valve is opened? 2. Does the top of the jar need to be ...
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1answer
329 views

Velocity of real gas molecules?

It is known that the velocity of ideal gas molecules can be computed using Maxwell-Boltzmann law of distribution of molecular velocities, with average velocity given as: ...
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7answers
3k views

How can kinetic energy be proportional to the square of velocity, when velocity is relative?

Let's start with kinetic energy (from los Wikipedias) The kinetic energy of an object is the energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a ...
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1answer
667 views

Relative Velocity and Momentum

The question is, "A $45.5~kg$ girl is standing on a $140~kg$ plank. Both originally at rest on a frozen lake that constitutes a friction-less, flat surface. The girl begins to walk along the plank at ...
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2answers
2k views

What does the velocity of a wave mean?

I know that the velocity of a wave is given by $v=\lambda f$ but what does this velocity represent in the physical sense. For instance, if I am told a car moves at a velocity of 5 $m/s$ I know that ...
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1answer
245 views

How much runway does the space shuttle need to land?

A textbook question proposes the following scenario: NASA needs to plan emergency landing sites for the Space Shuttle (RIP). There are a number of things to consider. The shuttle touches down no ...
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2answers
269 views

Negative sign of acceleration [closed]

This is the problem from our Physics textbook : A player throws a ball upwards with an initial speed of 29.4 m s–1. (a) Choose the x = 0 m and t = 0 s to be the location and time of the ball at ...
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1answer
428 views

How accelerometers sense constant velocity movements

There is something I don't understand about accelerometers. I know it's possible to make an Inertial Measurement Unit (IMU) by using "three" accelerometers. So with that, I could calculate the $x$, ...
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1answer
411 views

How do I find the initial velocity in this problem?

An X-ray tube gives electrons constant acceleration over a distance of $20\text{ cm}$. If their final speed is $2.0\times 10^7\text{ m/s}$, what are the electrons' acceleration? I know this ...
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1answer
367 views

From how deep into space can a human “skydive” back to earth? [duplicate]

Possible Duplicate: From how high could have Felix Baumgartner jumped without disintegrating like a shooting star? If a human can skydive from an altitude of 24 miles (39 km), and a ...
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2answers
1k views

How fast would a spaceship have to go to reach Alpha Centauri within a person's lifetime?

Given the recent news about the discovery of an "Earthlike" planet orbiting Alpha Centauri (our nearest stellar neighbour) it got me wondering just how fast would spaceship have to travel to be able ...
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1answer
283 views

How does Baumgartner slow his velocity so that the parachute can open up?

How does Baumgartner slow his velocity so that the parachute can open up? What is Baumgartner's speed just before his parachute opens? What causes his speed to slow down just before the chute opens? ...
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1answer
2k views

From how high could have Felix Baumgartner jumped without disintegrating like a shooting star?

Today Felix Baumgartner jumped from 39 kilometres high and reached the earth safely. Just considering friction, from how high can a human jump? I expect that from a certain height, he would have ...
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0answers
155 views

What direction a flag on an object moving in the wind shows?

"The flag of a ship that is moving northward with 10 km/h, points exactly southwestward. The windsock at the lighthouse points under 30 relative to the western direction southward. Calculate the ...
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3answers
2k views

Calculating car's acceleration from change in angle of hanging object?

The question essentially is based on a situation like this- A car has a small object hung from the cieling on a string (apparently at an angle of 0 degrees to the ceiling). The car is accelerating ...
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5answers
3k views

Physics behind Wheel Slipping

Lets say that I'm in a car and I apply full acceleration suddenly. Now, the wheels would slip and hence the car doesn't displace much. But If I start with some constant acceleration, slipping doesn't ...
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3answers
833 views

when an object moves downward, is its height negative?

the question is: A ball is thrown directly downward with an initial speed of 8.00m/s from a height of 30.0m. After what time interval does it strike the ground. so i went through the problem and ...
2
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0answers
81 views

Reaching the speed of light, rockets [duplicate]

Possible Duplicate: Double light speed Someting almost faster than light traveling on something else almost faster than light Well I've been wondering quite a long time about this ...
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0answers
180 views

2D Car Physics including Throttle

For a simulation for testing on automatic cruise control, I came across the equation: $$ v_{n+1} = (1 - k_1 / m) v_n + (1 - k_b) \begin{pmatrix} T_n \\ θ_n \\ \end{pmatrix} $$ where: $T$ = ...
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2answers
448 views

Lever Mechanics - How to formulate an ideal lever launch

Let's say I have a simple lever as shown below, and the lever is massless and the pivot is frictionless and there is no air resistance. I'm thinking the cradle for the projectile would have to have a ...
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1answer
251 views

Power, Force Velocity

In any case, if the force and power is constant , does velocity also need to be constant? If no, can you tell me a case. Further can this be extended for non-rigid bodies.
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2answers
1k views

Group Velocity and Phase Velocity of Matter Wave?

In quantum mechanics, what is the difference between group velocity and phase velocity of matter wave? How can it also be that phase velocity of matter wave always exceeds the speed of light?
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2answers
547 views

Calculating two particle position and velocity with each other?

I've calculated the displacements and average velocities of both particles. $A$ average velocity $= 1.1180m/s$ displacement is $11.1803m$. $B$ average velocity $= 0m/s$ displacement is $0m$. ...
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2answers
1k views

Difference between deltaV and specific impulse

When reading any literature regarding space propulsion, I keep getting about these terms deltaV and ISP or specific impulse. I know specific impulse is supposed to be the velocity the propellant mass ...
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1answer
736 views

Calculating velocities using Reference frames

Suppose an object A is traveling at a velocity of 100 m/s, and another object B is traveling at 105 m/s. With both the objects traveling through the same direction, taking A as a reference frame, the ...
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2answers
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How can an object's instantaneous speed be zero and it's instantaneous acceleration be nonzero?

I'm studying for my upcoming physics course and ran across this concept - I'd love an explanation.
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1answer
145 views

What is the quantity in physics that is advanced from speed? [closed]

What is the quantity in physics that is advance from speed? i know one is velocity, one is speed, one is acceleration.
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1answer
388 views

End position of movement factoring in deceleration

Ok I am hoping to apply this answer to a piece of software, but it uses physics to work out the result so I require some help in that department. I will attempt to explain this the best I can. I ...
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1answer
66 views

What is the shortest run needed for a “dropped skateboard” rider to reach 160 mph?

I just saw a great clip on the fastest skateboarder to date. He wants to reach 160 mph from a dropped board, but says his speed is limited by the roads currently available. What is the shortest run ...
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3answers
5k views

What is the physical meaning of diffusion coefficient?

In Fick's first law, the diffusion coefficient is velocity, but I do not understand the two-dimensional concept of this velocity. Imagine that solutes are diffusing from one side of a tube to another ...
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1answer
156 views

Determining Orbital Velocity

Is there any way to determine the orbital velocity of a point around another stationary point, if I don't know the mass of either of the points but know the force that gravity exerts and the distance ...
4
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2answers
5k views

Flow of liquid among branches

If water is flowing through big pipe is branched into 4 branches of small pipe. Lets say the flow is around 4 m/sec. I have the following questions: What will be the flow rate in each of the ...
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3answers
301 views

How does one measure velocity in space?

Just what the title states. Velocity, by definition, is the distance covered in a defined amount of time. How does one measure the velocity of a spacecraft that is not in Earth Orbit? E.g. Beagle ...
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3answers
857 views

Does an airplane's speed include the speed of the Earth?

After take off, does airplane's speed include Earth's movement/speed? Do airplanes turn with Earth movement/rotation?
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4answers
430 views

Why are coordinates and velocities sufficient to completely determine the state and determine the subsequent motion of a mechanical system?

I am a Physics undergraduate, so provide references with your responses. Landau & Lifshitz write in page one of their mechanics textbook: If all the co-ordinates and velocities are ...
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2answers
461 views

Is the escape velocity at Geosynchronous Earth Orbit 0km/hr?

Follow-up question to How long must escape velocity be maintained? Is the escape velocity at GSO 0?
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4answers
2k views

How long must escape velocity be maintained?

Escape velocity from Earth's surface is 11.2 Kilometres/second How long would one need to maintain this escape velocity to actually escape Earth's gravitational pull? Must this 11.2 km/s velocity ...
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2answers
503 views

Conservation of momentum equation, how do I factor out v0Final and v1Final?

I am trying to figure out an equation for conservation of momentum. So, If combined momentum before and after the collision is the same, and momentum is velocity times mass, then for 2 objects (A,B), ...
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1answer
637 views

How do I determine a component of relative velocity?

At a particular instant, a stationary observer on the ground sees a package falling with speed v1 at an angle to the vertical. To a pilot flying horizontally at constant speed relative to the ...
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1answer
507 views

speed of sound relative to density of medium through which sound travels

I know that sound travels faster in water compared to air and say faster in steel than in what're so What would the density have to be to cause sound to approach the speed of light
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2answers
2k views

What is displacement? Position relative to a reference point or change of position

What is the "official" or most useful definition of displacement in the context of kinematics? There are two common ones: Displacement is the length and direction of a line from a fixed reference ...
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2answers
189 views

Trains travelling at different speeds towards a station C

Here's the question: Consider two stations A and B located 100 kilometer apart. There is a station C, located between A and B. Now trains from station A and B start moving towards station C at ...
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2answers
574 views

Does acceleration at an angle to velocity change the direction?

During an interval of time, a tennis ball is moved so that the angle between the velocity and the acceleration of the ball is kept at a constant 120º. Which statement is true about the tennis ball ...
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2answers
2k views

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
649 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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2answers
1k 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
781 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 ...
2
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3answers
378 views

Train crash: are these situations alike? [duplicate]

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
204 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
6k 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 ...