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Questions tagged [speed]

Scalar quantity which is the magnitude of velocity.

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Is TMPH documented formula useful? [on hold]

In tires manufacturing TMPH is a limit scale and is its own unit, I think the formula was created by Michelin or Bridgestone and it is very similar to the force formula. $$TMPH = Ton Mile Per Hour$$ ...
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Can a projectile bullet kill? [on hold]

Today, I was watching a movie, in which a person shot a gun in air. The bullet went high in sky, became stationary for a moment and dived back and killing a non-innocent person by hitting him in head ...
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Calculate speed for each given point [closed]

Given this graph How to calculate the speed for each point starting from the (start point until point 5) I have tried solving it. But I am not sure if it's correct.
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Spiral lamp chane state speed

Question is how fast halogen lamp reach it full temperature, going from cold (not light) state to full light emit state. how fast in milliseconds it takes, imagine: if led lamp work instantly like 0 ...
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4answers
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Why does a car's steering wheel get lighter with increasing speed [closed]

I've noticed it is difficult to turn the wheels of a car when the car is stationary, especially cars without power steering, which is why the power steering was invented. However, I've noticed it ...
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Confusion on Horizontal & Vertical Components of a Parabolic Motion

This was a question I found about projectile motion, the question was what's the bike's speed when it took off. Using $S=ut + 0.5at^2$, the time taken to reach the ground is $0.505 s$, they used ...
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1answer
42 views

Why $g$ on equator is less than $g$ on poles? [duplicate]

I found this on my physics book. The book says $g$ on equator 9.78 $m/s^2$ and on the poles 9.81 $m/s^2$. Is it due to gravity?
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What is the difference between velocity and speed? [duplicate]

What is the difference between velocity and speed? could anyone describe it more specific? does velocity have direction?
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33 views

Does the weight on a car's wheels decrease with increasing speeds? [duplicate]

Ignoring the reduction in fuel weight as it burns, does the weight on a car's wheels decrease with increasing speeds? If so, by how much and is there a fomula for calculating that? At what speeds ...
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1answer
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Two containers that have the same volume (let say 500 liter) but are different in shape

I remember from school, one time a teacher explain us the following: two containers of the same volume, but one is thin and tall, and the second is short and wide. then if we fill them with water from ...
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2answers
77 views

Would a human age faster if these certain conditions are met?

So, a human would travel in a rocket in outer space. There is little to no gravity, and the pressure may or may not have an affect (?) on what i'm about to ask. It has been proven that when a human ...
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Why is a particle non-relativistic when its kinetic energy is small compared to its rest energy?

For example, nucleons in nucleus are in motion with kinetic energies of 10 MeV. Their rest energies are about 1000 MeV. Kinetic energy of nucleons is small compared to rest energy. They are hence ...
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Calculation of speed from accelerometer data

I am trying to use my accelerometer on my mobile device fitness band to find the speed of walking and running. I conducted my experiment of walking and running on treadmill where I asked a person to ...
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3answers
49 views

Effect on speed when decreasing the magnitude of acceleration

I'm struggling to come up with an answer to the following situation and question: "Suppose you are driving your car along a straight road in the positive direction and are speeding up (increasing ...
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2answers
75 views

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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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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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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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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120 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
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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
85 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
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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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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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“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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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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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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60 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
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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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158 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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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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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 ...
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1answer
55 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
71 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
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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
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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
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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
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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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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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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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119 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
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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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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
110 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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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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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
39 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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38 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 ...