The speed tag has no wiki summary.
-1
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1answer
33 views
What is the maximum speed of a change?
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, ...
-2
votes
0answers
39 views
Whats the theoretical max speed to go around the world? [closed]
I light of the new Scramjet tests I have a question thats been bogging me.
I live in Denmark, about the furthest i can travel is to New Zeeland which is roughly on the opposite side of the earth.
...
0
votes
1answer
45 views
Is there any case where one would use, snap, crackle or pop?
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 ...
37
votes
14answers
7k views
Why does kinetic energy increase quadratically, not linearly, with speed?
As Wikipedia says:
[...] the kinetic energy of a non-rotating object of mass $m$ traveling at a speed $v$ is $mv^2/2$.
Why does this not increase linearly with speed? Why does it take so much ...
1
vote
1answer
38 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 ...
2
votes
2answers
76 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 ...
2
votes
2answers
522 views
Why does an object with higher speed gain more (relativistic) mass?
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 ...
1
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2answers
80 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 ...
5
votes
2answers
1k views
How does electricity propagate in a conductor?
On a systems level, I understand that as electrons are pushed into a wire, there is a net field and a net electron velocity. And I've read that the net electron drift is slow. But electricity ...
1
vote
1answer
982 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 :
...
-5
votes
0answers
29 views
Multiplying Dimension Result [closed]
This might be a general question but I couldn't find any information on it.
If we multiply the first dimension by the second, we get area.
If we multiply by the third, we get cubic area.
What is ...
2
votes
1answer
130 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 ...
-2
votes
1answer
36 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... ...
-1
votes
1answer
87 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 ...
2
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3answers
54 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 ...
1
vote
1answer
51 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 ...
0
votes
1answer
710 views
Speed of a fly inside a car
A couple of weeks ago I was travelling in a car (120 km/h approximately) and I saw a fly flying in front of me (inside the car, near my nose, windows closed). I wonder how was that possible.
Does it ...
4
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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 ...
9
votes
4answers
572 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 ...
-2
votes
1answer
68 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 ? ...
4
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3answers
143 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 ...
10
votes
9answers
3k views
Accelerating particles to speeds infinitesimally close to the speed of light?
I'm in a freshmen level physics class now, so I don't know much, but something I heard today intrigued me. My TA was talking about how at the research facility he worked at, they were able to ...
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3answers
72 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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0answers
34 views
Special relativity: Related speed [closed]
If a sheep is moving in a velocity of 2mph related to a train, and the train is moving in a velocity of 2mph related to the ground what is the velocity of the SHEEP related to the ground.Is there an ...
1
vote
2answers
100 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 ...
1
vote
1answer
87 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;
...
0
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3answers
223 views
Imagining to speed up the Earth's revolution around the Sun until we feel its motion
If the Earth were revolving around the Sun much faster than it does, let's say 100 or 1000 times faster or whatever big-enough multiple of its actual speed, would we feel it? What sensation would we ...
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2answers
3k 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?
5
votes
1answer
224 views
What is the speed of time
When we measure the speed of a moving element we do it with the help of a reference frame. Now if we need to measure the speed of time, is it possible? Is time really has speed?
Thanks in advance.
3
votes
1answer
383 views
How does a particle of light reach the max speed of light? [duplicate]
Possible Duplicate:
How can a photon have no mass and still travel at the speed of light?
First of all I am not a professional physicist. I was curious as to how a particle of light can ...
0
votes
4answers
446 views
How does a train, airplane measure its speed?
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 ...
2
votes
1answer
179 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 ...
4
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4answers
2k 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.
6
votes
1answer
673 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 ...
6
votes
5answers
8k views
How to calculate average speed
I recently encountered a puzzle where a person drove 120 miles at 40mph, then drove back the same 120 miles at 60mph. The average of the speeds is (40mph+60mph)/2 = 50mph, so the total trip time ...
0
votes
1answer
105 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 ...
2
votes
2answers
426 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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5answers
1k views
2 balls falling hit the ground at the same time
There are 2 balls in a vacuum, next to each other but not touch. They are on the edge of a surface they will both leave the table at exactly the same time. One gets pushed harder than the other. The ...
2
votes
2answers
791 views
Speed of a particle in quantum mechanics: phase velocity vs. group velocity
Given that one usually defines two different velocities for a wave, these being the phase velocity and the group velocity, I was asking their meaning for the associated particle in quantum mechanics.
...
0
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0answers
26 views
Intuitive understanding of the equation for kinetic energy [duplicate]
Possible Duplicate:
Why does kinetic energy increase quadratically, not linearly, with speed?
I know this is one of the easiest equations out there and I've used it for years but its still ...
3
votes
2answers
117 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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votes
2answers
77 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 ...
2
votes
2answers
120 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?)
1
vote
3answers
1k 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, ...
3
votes
1answer
159 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 ...
7
votes
2answers
394 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 ...
4
votes
2answers
217 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 ...
2
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3answers
527 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 ...
6
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1answer
1k 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 ...
0
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0answers
58 views
Refractive index outside a vacuum [closed]
Refractive index is defined as n = c/v where c is the speed of light in the vacuum and v is the velocity of the light in a given material. Therefore refractive index outside of vacuum can be any ...
