Questions tagged [speed]
Scalar quantity which is the magnitude of velocity.
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What would the position vs. time graph look like if the velocity vs. time graph was a curve?
In my physics class we are learning about velocity vs. time graphs and position vs. time graphs for an object. We have learned that if the object is moving with constant velocity (this would be a ...
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3answers
45 views
How does the increase of heat increases the speed of a particle?
I am fairly new to the thermodynamics topic, I have been introduced that as the temperature of a particle increases, so does the speed of the particle; it moves faster. However, I never been told how ...
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Does multiple tensioning pulley affects the belt speed?
Consider a multiple pulley system with the main pulley(30mm) attached to the motor shaft and multiple tensioning pulley in different locations(all are 15mm), driven pulley of 15mm is connected to the ...
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41 views
Where does this equation come from?
I am investigating about viscosity of fluids and I found the following equation to calculate the viscosity:
$$\nu = \frac{2(\rho_s-\rho_l)\cdot g \cdot r^{2}}{9\cdot\Delta v} $$
The experiment ...
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1answer
64 views
Sound and gravity
How would heavier gravity (or lighter gravity) affect sound in terms of what I hear?
For example, say there is a planet that is capable of supporting human life, but it has heavier gravity than ...
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4answers
109 views
Why is escape velocity independent of direction of projection?
However, for any body projected with a velocity less then the escape velocity, the final maximum height will vary with variation in angle of projection. But why is this not the case in case of ...
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2answers
44 views
Why is $\sqrt{gR}=v$ same for finding Minimum and Maximum Speed?
I was wondering this: Why is the $\sqrt{gR}=v$ the same for finding minimum speed and maximum speed? Like if you are wondering the min. velocity for keeping a rollercoaster on track when on top of the ...
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1answer
34 views
What causes the wave velocity of longitudinal waves in a spring to changes as its length changes?
This video shows the velocity of longitudinal waves changing in a slinky spring as its length changes:
https://youtu.be/y7qS6SyyrFU?t=17
Something else responsible for the change in velocity ...
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1answer
36 views
A question on the properties of wave equations
When you change
$$y(x,t)=A\sin(kx-ωt+φ) $$
into
$$y(x,t)=A\sin(2kx-2ωt+φ), $$
does it double the wavelength because $k$ changes into $2k$ and double the frequency since ω is doubled?
If this is ...
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2answers
58 views
Is one side of earth faster at night and slower at daytime?
I'm reading Physics for Entertainment by Yakov Perelman and in it he says under "When we move around the sun faster" that at midnight the speed of the rotation of the earth is added to that of earth's ...
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0answers
25 views
“Speed” of gravity? [duplicate]
This is probably going to be a poorly written question, since I know really a little of physics.
Imagine a object of small mass, let's say a book, is floating in the universe in absence of any ...
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1answer
53 views
What is the interpretation of speed of a travelling wave, based on $\frac {\partial x}{\partial t}$ formula
Motion satisfies the wave equation if the following holds true
$$\nu^2 * \frac {\partial ^2 \psi} {\partial x^2} = \frac {\partial ^2\psi} {\partial t^2}$$ where $\psi$ is the vertical displacement ...
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2answers
66 views
What is the speed of the magnetic field?
There is an invisible magnetic field that pushes apart two repelling magnets What is the speed of that magnetic field?
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1answer
54 views
Interesting speed of sound observation
I just came by a table in the Class 11 Physics NCERT textbook, listing speeds of sound in different media.
Vulcanised rubber has an unusually low speed of sound $54\ \mathrm{m}/\mathrm{s}$ as compared ...
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3answers
75 views
What would be the minimum velocity of a particle performing S.H.M.?
We were asked a simple question on a test:
What is the maximum and minimum velocity of a particle performing an SHM?
Note here that we're talking about a generic standard SHM here. If the maximum ...
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3answers
143 views
What is the speed of a photon in water?
What is the speed of light in water? The speed of light in vacuum, divided by the index of refraction for water. And what is the speed of a photon in water?
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1answer
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Are my observations about the differences between average velocity and speed, in 1 dimension, correct?
I've been struggling to understand the differences between average velocity and average speed in 1 dimension; by doing some exercises I think I have figured it out, but i want to check if I'm correct.
...
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2answers
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Would a supersonic object without a combustion power source leave behind a contrail?
Contrails, as far as I understand them, are caused by either a pressure change that forces the condensation of H2O(g) OR by the release of warm H2O from a combustion engine. Most plane contrails, I ...
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2answers
62 views
Rolling objects released from rest: time down the ramp [closed]
Since we are given the values of I for each object, I was able to calculate the KE's of each:
the solid spheres had KE of $1/5mv^2$; the hollow sphere had a KE of $1/5 mv^2$, and the hoop had $1/2mv^2$...
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0answers
18 views
Speed and frequency of a transverse wave traveling through a string made of different materials [closed]
Say a wave generated by an oscillation machine is traveling through a string.
Will the frequency of the wave be the same across the string if:
The string is made up of 2 different materials with the ...
4
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1answer
45 views
Speed of solar system through dark matter halo
How is the speed of the solar system through the dark matter halo determined?
Direct dark matter detection experiments rely on this speed estimate. Assuming the sun/earth travel through the dark ...
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4answers
60 views
How to express acceleration changing direction? [closed]
There is a ferris wheel that is rotating at a constant speed. Acceleration magnitude is zero. How do I put it in an equation?
$a=0$ or $\vec a=0$. If there is another way please tell.
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3answers
122 views
Why speed = distance/time? [duplicate]
Is it merely an arbitrarily chosen definition that we created in order to quantitatively measure the speed of an object or is it some other way around. I want to know what's the reason behind such a ...
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1answer
38 views
The uncertainty of a toy car's measured average speed
Suppose I have a battery-powered toy car, and I am told to design an experiment which would allow me to determine the average speed of that toy car over, say, a meter, and to account for experimental ...
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2answers
109 views
Can I equate 3.9 to 4 here or it's just completely wrong? [closed]
I have this question:
A particle moving in a straight line covers half the distance with speed 3m/s. The other half of the distance is covered in two equal time intervals with speed 4.5m/s and 7.5m/...
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2answers
109 views
What is the drift velocity of an electron in a superconductor?
How is it,when compared to drift velocity in a conductor?
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34 views
Relationship between speed and power in wind/hurricanes
I was looking at hurricanes today when question crossed my mind.
Cat 1 Hurricanes are the ones going up to 95mph. Cat 5 goes above 157 mph.
That says a lot, but not all.
In motors or engines, RPM ...
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3answers
107 views
What determines the direction of a photon emitted by an electron?
When an electron loses energy and emits a photon, what determines the direction that this newly-created photon will travel?
The electron, being a point entity, has no internal physical structure, so I'...
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2answers
93 views
Speed of sound in a gas and speed of a typical gas molecule
Why is speed of sound in a gas less than the average velocity of the gas molecules? Is there an intuitive way to explain this?
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2answers
491 views
If an object moves at constant speed, does it necessarily have constant velocity? [closed]
If an object moves at constant speed, does it necessarily have constant velocity?
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1answer
49 views
If two bodies move constantly but with different speed, do they move with acceleration relative to each other? [closed]
If two bodies move constantly but with different speed, do they move with acceleration relative to each other?
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4answers
98 views
Is there an agreed upon physics definition of the term 'speed'?--for example, can it be negative?
The term speed is commonly defined as follows:
https://www.physicsclassroom.com/class/1DKin/Lesson-1/Scalars-and-Vectors
Speed, being a scalar quantity, is the rate at which an object covers ...
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7answers
4k views
Why isn't average speed defined as the magnitude of average velocity?
Speed is usually defined as the magnitude of (instantaneous) velocity. So one could assume that average speed would be defined as the magnitude of average velocity. But instead it is defined as
$$s_{...
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2answers
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What is the maximum speed of waves in stagnant water?
I want to learn the maximum speed conditions for a wave in a fluid. I think, Which mechanism causes this limited speed?
And How? The water is an understandable example for me.
By this question, I ...
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2answers
37 views
Calculating the Instantaneous speed
When we are calculating speed from the graph for a uniform motion the speed which get as an answer is actually the average speed and since in uniform motion the average speed is same as that of ...
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2answers
34 views
What is the speed of rotation of the magnetic field of a solenoid or current-carrying WIRE
How does one find the speed of rotation of the magnetic field around a current-carrying wire? or How fast is it circulating around the wire?
How does one identify the speed of rotation of the ...
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1answer
68 views
How to calculate the radius of a curve based on vehicle wheel speeds of a car
I have data of the 4 differen wheelspeeds of a vehicle during driving time. Based on that I want to calculate the radius of a curve it is taking. The following are my current thoughts that seem to be ...
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0answers
31 views
Speed of sound for a given frequency in a non-ideal gas (humid, room temperature air)?
I'm trying to understand what the speed of sound might be like for a given frequency in non-ideal and non-dry air.
Wikipedia states that speed of sound has a weak dependence on frequency in ordinary ...
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2answers
52 views
Speed of two objects orbiting around a central axis
This question has been bugging me for quite some time and i'm not too sure if i'm missing out some important factor in the understanding of this scenario:
Given two objects of equal mass and size ...
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1answer
92 views
Can acceleration be both the “rate of increase of velocity” and the “rate of increase of speed” in Physics?
A Dictionary of Physics (Oxford University Press) defines acceleration as:
The rate of increase of speed or velocity
However, from reading many other definitions it seems to me that acceleration ...
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1answer
70 views
How to find the speed of a single photon?
Firstly with the help of $E= hf$ I calculated the energy by taking the frequency of light as $6 \times 10^{14}\ \rm Hz$(the range of frequency of light is from $4$ to $8\times10^{14}\ \rm Hz$ so I ...
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1answer
74 views
Relation between The speed and Temperature of the molecule
I'm fully aware of Gay-Lussacs Law, but when I was reading Feynman Lectures on Physics volume 1, sir said that the temperature and the speed of the gas (Ideal Gas) are proportional to each other. But ...
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2answers
85 views
How instantaneous speed is defined as magnitude of instant velocity? [closed]
Let $s=$distance (a variable)
we define instantaneous speed = magnitude $\left[\frac{ds}{dt}\right]$.
However instantaneous speed is also defined as magnitude of instantaneous velocity
i.e. ...
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0answers
12 views
Speed of the Accelerating Expansion of the Universe [duplicate]
So I heard that the universe is exponentially expanding faster than light, but I heard it just expands 72 km/s per megaparsec, I am not sure what is what, if someone can give me a logical or ...
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1answer
41 views
Do blades on the same rotor really move at different speeds?
I was browsing Stack (great way to kill time at work) and I came across this question.
One of the comments confuses me somewhat.
@Zlelik No, helicopter blades cannot exceed the speed of sound - ...
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1answer
799 views
Why does sound travel faster in steel than in water?
I understand that sound travels faster in water then in air. Water is a liquid, and air is gas.
Water still has the ability to roll the molecules over each other (so water can flow), it has some ...
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1answer
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Einstein $E=mc^2$ equation what if we found an element energy? [closed]
I started research in time travel idea soon and iam asking what if there exist an element that gives energy equals to c^2 in the equation is the mass of this element is 1 ( i don't know the unit ...
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4answers
86 views
How can we calculate the speed from $E=mc^2$? [closed]
how can we calculate the speed of an object using the formula of Einstein $E=mc^2$?
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1answer
22 views
Wheel size for climbing up on inclined surface
I am going to make a Line follower robot which can climb up on a inclined bridge(45 degree with flat surface). If speed remains constant, Should I use bigger wheel to enable the robot to climb easily?
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2answers
35 views
Increasing speed of a car using more motors? [closed]
I am making a robot car with four wheels. Every wheel will be attached to a motor. If I use four motors and four wheels , will I get more speed then using two motors?(If all the motors rotate at same ...
