Scalar quantity which is the magnitude of velocity.

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75 views

Can a link between photons that don't exist at the same time provide communication with the past?

They have published something about a link between photons that don't exist at the same time. Does this means that it is possible to build a device that will receive messages from itself but these ...
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1answer
67 views

What is the maximum speed of a change? [duplicate]

Is there any limit on the speed of changing something? For example a particle is transformed to some other particle; This takes some time or is absolutely instant? If every change takes some time, ...
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1answer
81 views

Is there any case where one would use, snap, crackle or pop? [duplicate]

As we all know, if you differentiate distance with reference to time, you get speed, and likewise, differentiating speed you get acceleration. However, if you keep differentiating, to the rate of ...
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1answer
99 views

Gyro vs Accelero : Why is that assessment false?

Can we say that the Accelerometer's values are somewhat the integral of the Gyroscope's values ? I think that because I know that the velocity is the derivative of the position with respect to time ...
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2answers
3k views

Does inertia increase with speed?

I have heard that when the speed of the object increase, the mass of the object also increase. (Why does an object with higher speed gain more (relativistic) mass?) So inertia which is related to ...
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2answers
125 views

Currents and the Speed of Light

Why is it that currents don't flow at the speed of light, but rather significant ratios of the speed of light. I don't have any formal reasoning as to why they would flow at the speed of light-I just ...
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4answers
985 views

What is our estimated running speed on Moon's surface?

I was wondering if we have the chance to run on the Moon's surface, how would you expect it look like? I expect our velocity will increase for the same work we do on Earth, but not sure if this will ...
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1answer
351 views

How to find speed when accelerating down a slanted wire

I saw this picture on one of my social media sites with the caption, "I'd do this in a heart beat! Who's with me!" I was about to go balls to the walls and say, "I'm in! When and where??" But then ...
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1answer
247 views

How to smooth a path (and speed calculation) based on randomly timed coordinates? [closed]

first my actual problem. then my try on improving the current way of solving this with the wish for feedback or even a solution :) gpx file with lat/long, elevation and time. wanna calculate speed... ...
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1answer
295 views

Acceleration, velocity and speed

It is given that acceleration is constant, so can we infer that average speed and velocity are the same?? Moreover, circular motion is out of the question, as the function of x(t) where ...
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3answers
1k views

Wind effect on driving a ground-based vehicle

A friend of mine seems to think that wind affects the ground-speed of a ground-based vehicle in the same way airspeed affects an airborne aircraft. i.e. If faced with a 10mph headwind, your car isn't ...
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1answer
149 views

B-field and Magnetic forces, speed of a particle

Let's say I have a particle moving perpendicular to a uniform magnetic field of magnitude $x \ T$, and it moves in circle with a fixed radius. How do I find the speed of this electron? Initially I ...
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2answers
1k views

Help me get out of a speeding ticket

I was driving uphill from a complete stop for a distance of .4 miles estimated to take 1 minute in a navigation app. I was pulled over right after cresting the hill. The cop had me on radar going ...
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6answers
2k views

Why does the speed of light $c$ have the value it does?

Why does light have the speed it does? why is it not considerably faster or slower than it is? I can't imagine science, being what it is, not pursuing a rational scientific explanation for the speed ...
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2answers
820 views

Electric potential energy and speed

If we have electric field and we put electron there , the electron will move in the opposite direction as the electric field. My question is electron in that direction will speed up or slows down ? ...
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3answers
251 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
525 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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5answers
1k views

comparing torque and 0-60 speed in cars

Im looking a two cars, both are the same model but ones got a 2.0L turbo petrol engine and ones got a 3.0L turbo diesel engine. These are the full specs 2.0L Petrol 3.0L Diesel what im ...
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1answer
136 views

Weightlessness on Earth

Would the following work? Imagine one would 1) create a straight 4000 km long tube (at ground level), following the curvature of the Earth, wide enough to hold a pod the size of an aircraft cabin; ...
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1answer
1k views

Where to find the current positions and velocities of the planets?

I've written a program which simulates the motions of planets and other bodies. I'd like to run it on our own solar system, but to do so I need to know the current positions (preferably in ...
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1answer
191 views

Would an object hit the ground faster when it gets launched vertically upwards or downwards?

A while ago I had a discussion with someone about the speed of an object when it hits the ground. When does an object hit the ground faster: When you launch the object to the sky so it can fall ...
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2answers
6k views

How can I calculate the wave propagation speed in a copper wire?

First of all: I am a computer science student, so I don't have much knowledge of physics. So please keep your answers simple. I recently learned something about circuit design and its problems ...
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2answers
966 views

How to relate speed of sound with relative humidity?

I am exploring the idea of measuring the humidity of a space using sound waves, however I am having trouble finding a mathematical relationship between the speed of sound and the humidity level. ...
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2answers
113 views

super-jump air balloon [closed]

We have the following objects: a 80 kg person a rope of negligible weight a balloon filled with helium, which can lift for around the same weight, 80kg. My question is, which of the following ...
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3answers
8k views

Why does an object with higher speed gain more (relativistic) mass? [duplicate]

Today, in my high school physics class, we had an introductory class on electromagnetism. My teacher explained at some point that an object with a very high speed (he said it started to get somewhat ...
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3answers
5k views

Is the same amount of electricity used for ceiling and table fans on different speeds?

We use ceiling and table fans in home which are can be set to low or high speeds using regulators. I want to ask that does it uses or consumes same amount of electricity at different speeds? Here, ...
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2answers
251 views

Speed of Entropy change

If time in systems moving with different speed goes differently, does speed of entropy change differ in these systems? (is "speed of entropy change" a valid term? can we compare them?)
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1answer
280 views

Does $\lambda\nu = c$ hold for all the waves in the universe?

Are all waves in the universe the same as electromagnetic waves? Basically, my question arises from an equation I found in my chemistry textbook: $$\lambda \nu ~=~ c.$$ This states that the ...
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2answers
879 views

Is it possible to travel at precisely the speed of sound?

I've been talking to a friend, and he said that it's impossible to travel at exactly the same speed as the speed of sound is. He argued that it's only possible to break through the sound barrier using ...
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2answers
1k views

Why does the wheel of a car appear to be moving in opposite direction?

When a car is about to stop, the speed of its wheel reduces. Why do we see or feel that the wheel of the car is moving in the opposite direction? This can also be observed of a fan at home. So why ...
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4answers
4k views

How Felix Baumgartner has reached the speed of sound quickly

I have watched Felix Baumgartner freefall; but I wonder how Felix has reached the speed of sound quickly, in a matter of some seconds, then we had no idea of its speed? Any explanation please.
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5answers
2k views

Why would a fat skydiver fall first in free fall?

I was having one of those obnoxious conversations with a friend where he was arguing that a fat skydiver would reach the ground faster than a skinny skydiver. To me it seemed as obvious that the world ...
2
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1answer
470 views

Which speed can an electric scooter reach on a given slope?

Electric scooters are always "given" as "working with slopes up to xx%", but what does it mean? Given motor torque and power, scooter+driver weight and wheels diameter, how can I determine at which ...
6
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1answer
7k views

How fast would someone have to run to run over water?

I was thinking about Flash, the superhero, or the little boy in the Incredibles. There is one Yahoo answer that doesn't answer a lot. Especially, I don't think surface tension would help a lot for a ...
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1answer
147 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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3answers
784 views

How will you measure speed in km/hr in space?

How is the speed of an object in space measured? Also more importantly how do you measure your own speed in space? On the road we use a speedometer which tells us the speed easily. How is it done in ...
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2answers
2k views

Can human hand move at a speed rate like this baseball pitch or is it just the speed of ball?

Fastest baseball pitch ever recorded was in 1974 at a speed of 100.9 miles per hour. Does this mean that the pitcher's hand was also traveling at that speed or just the ball? Is it physically ...
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3answers
3k views

Relation between Newtons and Kilograms

Work is expressed as W=F*d, where the F is in Newton, d is in meters and result ...
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1answer
188 views

Someting almost faster than light traveling on something else almost faster than light [duplicate]

Possible Duplicate: Travelling faster than the speed of light Double light speed Lets say that an airplane can fly at 4/5 of the speed of light, and I can run at 2/5 of the speed of ...
0
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3answers
686 views

Finding instantaneous speed in MPH given acceleration, RPM and gear ratio

I am still trying to figure out how to (semi) accurately model instantaneous speed after having found acceleration. I have found that at higher RPMs, the resultant acceleration will be lower. I was ...
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3answers
815 views

How to determine an exponential acceleration curve?

I've always been not so bad in mathematics, but I'm terribly bad at physics. For me, abstract concept are totally understandable, but when it come to reality, I'm lost ! So, for my job, I need to ...
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3answers
3k views

Does friction decrease as objects move faster against each other?

I was told that the faster two objects move against each other, the less the friction between them would be… compared to if they were moving slower. In physics class, we always use the coefficient of ...
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2answers
20k views

How exactly does mass affect speed?

I konw that mass affects weight (force), so how does that relate to speed? F=ma. so how does all this affect speed?
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1answer
2k views

Which derivation of drift velocity is correct?

In the derivation of drift velocity I have seen two variations and want to know which one's correct. $s=ut+\frac{at^2}{2}$ Assume that the drift velocity of any electron in any conductor is : ...
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1answer
1k views
0
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1answer
101 views

A Satellite's Perspective

If a planet is spinning east to west and there is a satellite spinning from west to east... Can the satellite travel at a speed sufficient to make the planet appear, from the vantage point of the ...
6
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1answer
4k views

How does one derive the equation for the speed of sound?

In my acoustics books I see $$c^2 = \frac{\mathrm{d}P}{\mathrm{d}\rho}$$ where $c$ is the speed of sound, $P$ is the pressure and $\rho$ is the density. Where does this equation come from? In my ...
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1answer
351 views

Laws of aerodynamics after breaking the sound barrier

my knowledge of physics is not very extensive, so I hope my question isn't too stupid. I know that when (for instance) a plane breaks trough the sound barrier, the laws of the aerodynamics change. ...
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1answer
233 views

How to calculate the dependency of speed and weight of a servo? [closed]

Here is a digital servo: Servo By using the information of details of that thing what is the way to calculate the dependency of the speed of the movement of the car if the load upon the servo is N kg ...
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4answers
1k views

How does a train, airplane measure its speed? [closed]

I always get the doubt about this. I know that a bike measures its speed based on the motion of its front wheel. So what is the case with train? Is it same principle? Then what about an airplane? Is ...