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How do I calculate rolling resistance for tire on pavement?

First condition assuming perfect rolling, no slip, from what I understand is that the rolling resistance coefficient can be calculated as the displacement arm of the normal force the tire "feels", in which should be equal to the force about its…
julesverne
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Why did Volkswagen use special software ONLY during emissions testing?

As we all know, Volkswagen is in the middle of a scandal centered on its use of special software to lower tailpipe emissions during standard emission testing protocols. What I don't understand is why this software needed to be switched off in other…
Gremlin
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Scratchless Glass against steel

I want to implement a piece of glass to set various pieces of steel on and take picture through it. The pieces of steel weigh anywhere between 20-150 lbs. The purpose of the glass is so pictures can be taken of both sides of the piece at the…
Timmy
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Creep of the materials

Does creep exists for all materials at any stress at room temperature? I searched for this and could not find any answer other than creep isn't significant at low stresses and low temperatures. What I want to know is if the creep is present at low…
Duke William
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PWM flow control and thrust

If I have a water pump and a fast solenoid valve (can be open or closed) and turn on my pump at a constant voltage and apply pulse width modulation to my valve. Would the resulting thrust created at the water output be constant and can it be…
Mehdi
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What is "Bernoulli-Lift", and why does it only account for 20% of an airplane's lift?

Whenever the question "Why do airplanes fly?" is asked (e.g. »What really allows airplanes to fly?«, »How an airfoil works?«) at a certain point the following is cited: Bernoulli's principle accounts for 20% of an airplane's lift… In a very…
rul30
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Equating $\frac{dp}{dt}$ and $F$ at a hydraulic jump?

A journal I am reading about circular hydraulic jumps provides the equation and I quote: $H$ Depth after hydraulic jump, $h$ depth before hydraulic jump, $V$ velocity after hydraulic jump, $v$ velocity before hydraulic jump, $R$ radius of hydraulic…
MadCommy
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Question about "uncertainty"

I'm a bit confused about all the different "definitions" of uncertainty? One can calculate "uncertainty" of a single measurement by simply checking how accurate the tool that is being used to do the measuring is. One can also calculate "uncertainty"…
Nova
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Which lubricant (oil or not) to use if I want to prevent sticky/gummy buildup?

I am currently tinkering with typewriters and two things striked me when I started to read about their maintenance: They are supposed to run almost completely dry, except for a very tiny amount of lubricant at very specific points; Gummy or sticky…
heltonbiker
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Origins of the "threaded fastener pullout formula"

I was looking through NASA's document for "Installation Torque Tables for Noncritical Applications" and noticed their formula for the pullout load of a fastener on a certain material. It goes as follows: $$P = \frac{\pi\cdot d_m \cdot F_s\cdot…
TwoWaySpeedOfLight
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How do I conduct an experimental modal analysis with a three-axis accelerometer?

How can I compute the Frequency Response Function (FRF) if I use two three-axis MEMS accelerometer to measure the input excitation and output response? I have read from some books that the FRF can be computed as the ratio of response to excitation,…
ice_lin
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How to make a weather buoy more stable?

I'm designing a weather buoy as a school project. I have read that the metacentric height is a good measurement for buoy stability and is relatively easy to calculate. This page says the metacentric height $MG$ is given by the…
5TableLegs
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12V outdoor lighting power consumption

In an 12v outdoor lighting circuit, is our electrical consumption (our electrical bill) determined by the 50W 12V bulb that is connected to the transformer, or the 300W rated output of the transformer? I have equally received two answers;…
Steven M
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Best traffic control device/system for given situation

I am familiar with the round-a-bout/traffic light pros and cons, however, I've been tasked with deciding on a solution for the given parameters below. Currently, there is a two-way (four lane) road with a speed limit of 35 mph. Rough traffic counts…
Anthony Burleson
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Liquid splashes - who researches it, and why don't all urinal mats look the same?

I normally wear shorts in the summer, at which point I become very aware of the problem every man knows about - splashback of pee from urinals. No matter how you stand or aim, the inherent splashing effect of a stream of liquid hitting a surface…
Graham
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