Most Popular
1500 questions
11
votes
5 answers
Practical setup to measure angular velocity
I have got a spinning top from a Canadian manufacturer, and I am deeply amazed by how neatly it spins.
My interest in physics has led me to try to find out at what top speed I can spin the top and how that compares to other tops made from other…
DK2AX
- 355
- 3
- 12
11
votes
1 answer
Will a sacrificial anode protect any length of metal that it is connected to?
When using a sacrificial zinc anode, is there a limit to the distance that its protection will extend?
The protection works based on electrical conductivity, so distance would seem to affect the performance of the anode based on resistance. On the…
hazzey
- 10,730
- 11
- 46
- 96
11
votes
5 answers
Would a "lifting body" design be useful for a train car?
Lifting Body
The idea of a lifting body design is to shape a vehicle's body in such a way as to produce lift without wings. Research has shown that this can be an efficient method of reducing drag while still providing lift.
This has typically done…
hazzey
- 10,730
- 11
- 46
- 96
11
votes
1 answer
Detailed dimensions of an aircraft engine compressor blade
I am working on rub-induced vibrations in compressor stages of aircraft engines. The work is carried out in partnership with a company, therefore there is a limited amount of it that could be published openly.
Is it feasible to release open source…
Nicolas
- 332
- 3
- 15
11
votes
2 answers
Is a chair with N+1 wheels ever less stable than a chair with N wheels?
My workplace has a policy to provide standing desks upon request, but no policy to provide chairs of matching height. (I work for the government...) We can buy our own, or build our own. However they added a stipulation that the chairs must be…
Dennis
- 263
- 1
- 4
11
votes
6 answers
What fundamentally distinguishes cavitation and boiling as different phenomena?
Cavitation and boiling are names for phenomenon that both involve sudden appearance of bubbles of vapor within a liquid, and in both cases they happen when the local hydrostatic pressure is lower than the vapor pressure of the fluid, but that…
uhoh
- 339
- 4
- 21
11
votes
3 answers
Why would a bearing plate that further concentrates load onto small surface be used?
Here's a photo of a bearing plate where a bridge reinforced concrete beam meets the earthfill
The bridge span is about 20 meters long and consists of two reinforced concrete beams each resting on two bearing plates like the one shown - one plate…
sharptooth
- 2,129
- 19
- 28
10
votes
9 answers
Why aren't counterweights used more for garage doors?
One of my garage door torsion springs broke again. It makes me wonder why some sort of counterweight system isn't used instead. Torsion springs seem to have a 90 day warranty generally and are "rated" for up to 15,000 cycles. It seems like there…
Jason Goemaat
- 211
- 1
- 2
- 7
10
votes
5 answers
Difference in energy consumption between empty fridge and fridge filled with bottles of water
I have about 12 bottles of water. If I want to minimize the energy consumption of my refrigerator, should I put these bottles in the fridge or leave them out?
fronthem
- 475
- 4
- 13
10
votes
2 answers
Best way to get rid of turbulent flows?
I am making a testing facility for pumps. This facility has to be able to handle 500 m3/h with at little turbulence as possible. The basin itself is 5 meters long, 2,5 meters wide and 2 meters tall. The water level in the basin is kept at 1,9…
Arjo
- 103
- 5
10
votes
1 answer
How to calculate Power of motor when used as a generator?
How can you calculate how much power can be generated by a motor when used as a generator (like a motor used in a wind turbine)?
Does the power depend on how fast the magnet is rotated? If so, is there a equation that lets you know given the rpm,…
user510
- 313
- 1
- 3
- 9
10
votes
1 answer
Where did I go wrong conceptually when attempting to calculate the maximum force on a truss at a given joint?
In the problem statement below, the question states to find the maximum load $\vec{P}$ that the truss can support. My method of approach was:
Draw a FBD for the entire structure.
Generally I would identify all external forces, however for this…
Hunter
- 203
- 2
- 7
10
votes
1 answer
MIMO (multi input - multi output) system decoupling method
A MIMO system with 2 input and 2 output decoupling method to a SISO system is described in many articles and books. How about m*n size transfer functions systems? How can we generalize the method for example to 3*3 or 3*7 MIMO systems?
Here is a 2*2…
lahidj
- 141
- 1
- 5
10
votes
3 answers
How do you determine the accuracy of a measurement device?
Lets say you have a measurement device of which you do not know the accuracy, and a reference measurement device. Both measure a variable $x$. The range of interest is $x_0
JHK
- 1,638
- 2
- 19
- 29
10
votes
1 answer
Response of a system to a step function (Heaviside function)
I'd like to compute the response to a step function of a electrical/thermal system. Generally I can "easily" compute the transfer function $H$:
$$H(\omega) = \frac{V_{out}(\omega)}{V_{in}(\omega)}$$
Since the Fourier transform ($\mathcal{F}$) of the…
Worldsheep
- 383
- 1
- 10