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📰 Hardware News
Microsoft and OpenAI are reportedly negotiating to invest up to $500 million in the humanoid robotics startup Figure AI, aiming to pioneer the deployment of autonomous humanoid workers globally. This significant investment could elevate Figure AI's valuation to $1.9 billion, potentially making it the first unicorn in the humanoid robotics sector. Figure AI, founded in 2022 by Brett Adcock, has attracted top talent from renowned organizations like Tesla and Boston Dynamics, emphasizing the growing competition and innovation within the robotics industry.
NASA and Lockheed Martin unveiled the X-59 "quiet supersonic" aircraft, designed to fly faster than the speed of sound (925 MPH) while reducing the sonic boom to a "sonic thump" to minimize disruption. This experimental aircraft, emerging from years of development and a significant NASA grant, showcases a highly aerodynamic shape and an innovative cockpit design featuring a 4K screen for visibility, named the eXternal Visibility System (XVS), due to the impracticality of a forward-facing window. The X-59 aims to pioneer quiet commercial supersonic travel over land, with its first flight scheduled for later this year
👶 Meme Of The Week
🙋♂️ Interview Practice Question of the Week
What is this? How does it work? What is it made out of? How would you manufacture it?
✅ The Answer
Many interviewers, especially at startups, like to throw 1 or 2 curveball questions in that don’t fit the traditional mold and are difficult to prepare for. Here’s an example!
Though initially presented as a question of recognition, there’s a lot that can be gleaned from your approach to figuring out use case. As with most technical interview questions, the keys are problem solving and first principles!
Question 1: “What is this?”
Odds are that you won’t know what at least one of the items (or even any of them). Start by taking a closer look at the item and voicing any unique or identifying characteristics that you observe. This wouldn’t be a very interesting question to ask if everyone knew what the object was, so don’t sweat the answer for now, just ponder aloud.
Often, after going through some ideas, the interviewer will ask you a leading question. Here are some example identifying features (note that the list is not remotely comprehensive):
The Nail
The head is off-center and flat(ish)
It has a square cross section
The tip is long and flat
There is rust . . .?
If this interview was in person, and you were handed the physical nail, you would also see that it is roughly 5-6 inches long
The Waffle
It is a ridiculously large metal part
There are a ton of pointy . . . aerodynamic features? Thermal features? Surface area appears to be reasonably high and of some concern which either means high drag or high heat transfer rate (probably). The points could also work as an impact surface or abrasive surface for a very large object, but this is less likely since the impact object or object to be abraded would be stupendously large.
There are some extra support members toward the ends. Perhaps reminiscent of a hinge? That’s probably the attachment interface.
Only one side has attachment features
The Roller
Two terminals top side, one on each side of the object. This means electricity is transferred through the roller, possibly to heat it via resistive heating? Perhaps those squiggly traces need to heat up?
The texture and color (hideous) are both well defined. Perhaps this is used as a tool for something else?
Looks like it was designed to be mounted on a flat surface,
Possibly rotates, but probably not quickly as there are no bearings visible.
Size is difficult to tell from this image except for the terminals and attachment nuts holding in the bracket, but those imply that this component is roughly arm sized.
Once you have made some observations, disguised as you “thinking,” it’s time to make your first guess. The interviewer wants you to guess relatively early on into the interview because they will have follow up questions they want to ask.
The Nail
I would probably at this point guess that is was a nail used in large timber construction . . . maybe log cabin building?
The interviewer would say something like “You’re so close!” and then follow up with a leading questions like “why is the head off center?”
I might say to fasten something thin to the large wood beam.
This would then go back and forth until either I figured out what it was or the interviewer believed I got sufficiently close
It is a railroad spike.
The Waffle
This is a really hard thing to guess if you haven’t seen it before. I might ask the interviewer what material it is made of?
If they answer that and say it is aluminum, that could be a decent clue (I probably could have guessed that by looking at it and not seeing any rust).
Given how large it is (appears as one piece) and that it is made out of aluminum, with extensive post machining it would have to be for aerospace or actual space to justify the cost.
That would then lead me to believe the points in fact had aerodynamic and/or thermal implications.
I might guess it is a specialized wing for a satellite.
Without leading questions, it would be difficult to guess without prior knowledge, but this is a grid fin used by SpaceX to control flight during landing.
The Roller
Electricity intentionally runs from one side to the other, but not in a manner which appears to power anything else. That means it’s most likely a large passive electrical component. That limits our guesses substantially.
Capacitors tend to have both of their leads on the same side.
Inductor? Coiling could be internal.
Transistors require 3+ leads and usually don’t get so large (would just get swapped with a relay at higher power)
It could be a diode, those are tubular and often get hot.
Finally the most obvious but maybe less likely guess would be just a large resistor. I would probably guess this after “ruling out” the other items above. If I mentioned one and in fact it was that thing (let’s say the diode), the interviewer would probably press me more on why I ruled it out.
It is in fact, a very large resistor!
The follow up questions. Now it’s time for you to show off your extensive knowledge of material selection, fabrication and electronics (jk . . . kinda).
The Nail
The most obvious question they would ask, is what material is it made of?
Usually I would first list characteristics the railroad spike would need to exhibit and then match it to a material, ruling out other materials as I went down the list giving little justifications.
In my mind I would point out the need for the spike to be inexpensive, strong, handle many hammer blows (this might rule out iron which can be brittle) and point out the rust I was seeing. Also, I might mention that railroad spike have been around for a very long time so newer materials like titanium (and even aluminum) could probably be ruled out (also based on cost).
After all of these observations I would arrive at a low carbon steel.
They might follow up with questions about why there is a square cross section or long flat tip. I would answer these with the same strategy as above.
The Waffle
There are a million questions they could ask you about the grid fin.
What material? This is where you would dive into your materials knowledge and point out that a 7075-T6 aluminum is probably the best bet, though it might need some coating/anodization to protect from re-entry heat. You could bring up titanium (3x the melt temp) though would want to highlight how expensive it is to manufacture (the current Falcon 9 grid fins are now titanium though they used to be 6061-T6 aluminum).
Why the form factor? The three things that jump out to me here would be the the aerodynamic effectiveness for a very low volume/weight structure with high surface area (good cooling and high drag), ability to tuck away for takeoff, and finally the small hinge moment relative to a much larger fin system.
How is it manufactured? It looks like a single piece of material so the best bet is casting then post machined. Even so, it would be a mega large casting. Before giving that answer I might highlight some different manufacturing techniques and pros/cons to demonstrate additional knowledge of manufacturing.
The Roller
I don’t think you would get too pressed on this one for a mechanical engineering interview beyond the classic “what is it” question. They could ask about what material is on the inside of a resistor or how does a resistor work. Worst case, you’ll get a follow up question on thermal dissipation of the resistor in which you’ll have to do a resistance diagram and basic calculations (ironic perhaps, doing a thermal resistance diagram on a resistor itself). Also, it’s always good to know the basic electrical formulas (pL/A). These questions meant to test first principal thinking about what is “resistance” at its core. If you haven’t already seen or thought about it, consider how you would design a potentiometer (variable resistance resistor)!
To reiterate, these curveballs are almost never purely about the right answer, it’s more about getting a feel for your thought process! They’re meant to be fun, so even if you can’t prepare as easily for them, don’t sweat it. Just start at first principles and think things through!
What are some resources you recommend for learning about material choices and general material knowledge?