# Tag Info

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### Unit of "cN.m" used on torque wrench

100 cN.m are 1 N.m The c before the N.m is pronounced centi. It's a standard SI prefix. 1 c ...
• 24.3k

### Variation of LED light as a function of distance

All EM radiation from a point source falls off in intensity with the square of the distance. LEDs can't magically change this basic physics. LEDs can be quite directional in their emission pattern. ...
• 11.4k

### Can a blimp enter Mar's atmosphere as a glider?

I assume that the person you are referring to is Felix Baumgartner, who achieved a maximum speed of Mach 1.25. While this speed is very fast, this is nowhere near the speeds achieved by meteorites, ...
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### What prevents the use of electric engines to assist with spacecraft launches? (Space Shuttle Booster Supplement)

Electric turbine engines First off, "electric turbine engines" don't really exist. What you're probably thinking of is an electric version of the jet turbine engine, which is a type of ...
• 1,210
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### Difference between partial derivatives and derivatives in physics

For a detailed explanation search WikiPedia for derivative, partial derivative and ...
• 540

### How can I vaporize metals?

The easiest way to vaporize a metal is to create a filament of the metal. Heat the filament in the vacuum to its sublimation (vaporization) temperature. Alternatively, when the metal cannot be shaped ...
• 2,943
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### What is the difference "maximum" shear stress and shear stress

The difference is in the assumptions. The first "shear stress" is simply assuming the stress is uniform over the cross section. As a result, we see a shearing force $P$ shearing a rod of uniform ...
• 5,333
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### How can I accurately measure the actuation force of small buttons (<1cm diameter) using home equipment?

If you want a quick and somewhat inaccurate hill-billy engineering answer, I would take a digital kitchen scale and place the PSV ontop of it, tare it, then load up a program to test the buttons (game,...
• 165

### Ceiling or table fan better

There are far too many factors involved to definitively state that a table fan cools more than a ceiling fan or vice versa. For starters, there are different styles of both. It also depends highly on ...
• 571

### Can graphene really be made in a modest lab at home?

The short answer is, anyone can make graphene, but knowing you did or doing anything with it requires a bit more equipment. I work with people who work with graphene. This is not the only way to ...
• 126

### What is the most efficient way to ionize air?

It will depend on the degree of ionization you require, as well as the pressure of the air passing through the ionization region. Your gas will not likely be at STP if the air is moving through a ...
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### Unit Conversion for Mass Density

First Part Simplifying the $$1 \ lbf = 1 \ slug .ft/sec^2$$ then $$1 \ lbf \ sec^2 / in^4 = 1 \ (slug .ft/sec^2 ). (sec^2/in^4) = 12 \ slug /in^3$$  12 \ slug / in^3 * (14.6 kg / 1\ slug)*(in/25....
• 228
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### How would I drop something directly in the middle of a vertical pipe?

Illustration following up from the comments We used vacuum to hold the ball bearing being dropped, from above. The ball was hand placed up against the output port of a manifold. Around it was open air....
• 1,550
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### Dissolved gas release from liquid

I've seen similar action when a straw is in a glass of soda. Bubbles form on the straw, causing it to "float" upwards, then the bubbles break free and the straw sinks again. Rinse, lather, ...
• 4,209
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### Could a spinning permanent magnet's interaction with the Earth's magnetic field propel a boat through the water?

Like anyone who has used a compass knows, earth's magnetic field does exert a force on magnetic objects. In theory this force could be harnessed to do work, but in practice it is too small to be a ...
• 46

### Is there a way to simulate the drag effect created by acceleration while in a stationary object?

The rides in Disneyland do a great job of combing the visual cues of the ride with actually accelerating the vehicle or boat or rocket but in a carefully designed short span giving the impression of ...
• 22.4k

### Which has more density: 100 °C steam or 100 °C dry air?

There's an air of 'lmgtfy' about this question... Wolfram Alpha is a great resource for quickly finding information like this. You can see that the steam is significantly less dense than the air, at ...
• 7,761

### How do measures of error or uncertainty change, when the underlying variable is transformed?

In general, if the calculation is multiplication by a constant, then you multiply the uncertainty by the same constant. That's assuming that "uncertainty" refers to something like standard deviation, ...
• 3,751
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### Recreating Focaults Pendulum

There are two simple options for the bearing The first is to suspend the bob from a flexible cord passing through a fairly tight grommet so it will maintain a constant point of contact in all ...
• 15.2k

### Variation of LED light as a function of distance

As Olin mentioned, the emission pattern is quite anisotropic. It depends on the LED. Most have primary lenses which all have unique emission patterns. One example of such can be seen in the Cree X-...
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### Variation of LED light as a function of distance

As Olin said, LEDs, even without their lens cap, are quite directional. If you want a decent point source, the typical approach is to use an external lens to refocus the LED output as best you can ...
• 4,209

### Can using different types of alcohol in a cloud chamber produce different particle tracks?

The only major difference the alcohol choice will make is the ionization energy. While the ionization energy for Methanol is 10.85 (source), ethanol is 10.62 eV, while Isopropyl is only 10.10 eV. ...
• 5,333
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### Different Color Intenensities from simple ON/OFF RGB subpixels

If I understand that picture correctly, the brightness is a function of how many subpixels are turned ON in a given image frame. Your eye integrates all the photons it receives, so if all 16 red ...
• 4,209
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### Buoyance+torque generated force

Edit: Added the requested drawing + corrected formulae for the 4 bar setup As Carl Witthoft mentioned, the buoyancy force $F_1$ from the block is proportional to the submerged/displaced volume (\$V_{...
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### How to make a pulley system with a mechanical advantage of 0.5

What you need is a block-and-tackle, namely a gun-tackle. Source The general trick to determine advantage is how many verticals you have bearing the load (other than the end you are pulling from). ...
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### On construction of a triangular interferometer like LISA

If I'm understanding your question correctly, you are asking how you can build a functional laser interferometer. That is a pretty complex topic and impossible to cover in detail in a single answer. ...
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### Can chemical vapor deposition chambers be used to lay down thick layers of metal?

you do not need a CVD system to deposit metals, a planar magnetron sputtering system is more suitable. But for layers of order ~1mm in thickness you would be better off with an electroplating process.
• 14.7k