Technical Questions Asked in Mechanical Engineering Job Interviews
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- เผยแพร่เมื่อ 3 ก.ค. 2024
- This video discusses the technical questions that Apple ask in their job interviews for roles in Mechanical Engineering, Product Design Engineering or Manufacturing Engineering. The six questions we go over in this video can be found on Glassdoor and were also asked in the interviews we had with Apple. The six questions as well as timestamps for each question are as follows:
00:29 How to Reduce a Cantilever Beam’s Deflection?
02:13 The Boat Question
04:58 What’s the effect of shortening a spring on stiffness?
05:50 Compare the Stress-Strain curves of Steel and Aluminum
08:18 How are iPhones manufactured?
09:14 Steel vs Aluminum…how to distinguish between them?
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The Spring Stiffness question is worded oddly.
There could be two meanings to this question:
(1) If you are trying to evaluate the Spring Constant (k) when you know Spring Force (Fs) and displacement (x) - then its a simple matter. For spring force Fs - the smaller the displacment is the stiffer the spring has to be. If the same spring force - stretches the spring much more - then that means you have a 'lighter' spring or a lower k value.
(2) If the question meant how do you effect the actual physical/natural spring stiffness - then that is a much more complication question related to Spring Design. That has to do with the material, diameter of spring wire, # of coils, the angle of the helix of the coils etc.,..
Basically- spring stiffness is a natural property of the spring as a product - it doesn't change and is fixed.
That's what I am thinking too. They asked how would it effect the spring if they were to shorten the length of the spring and not compress it. So, maybe they had to answer the question through a design POV view.
I believe K would still increase in case 2(without finding my mechanisms design textbook). you can model the “cut” spring as two springs added in series. When you add two springs in series the combined K is less than the individual k(s). Thus, it is reasonable to assume that the Cut spring will have a higher stiffness than the original.
Yep. I went straight to the comments looking for this.
This response makes me so happy haha. That's what I thought too
1) How to reduce a cantilever beams deflection
• First start by sketching a simple cantilever beam with a forcing acting vertically down
Write the general deflection equation: δ= (FL^3)/3EI ; F = force
L = Length of beam, I = second moment of area, E = young’s modulus (stiffness),
To reduce deflection you can reduce the force(F) or reduce the length(L)
To reduce deflection you can increase the young’s modulus(E) i.e. the stiffness of the material or increase the second moment of area by increasing the height or width for a rectangular beam (note I = (bh^3)/12, also most beams are rectangular because they are easy to construct, formwork is cheap and easy to erect) or if the beam is circular increase the diameter
2) The Boat Question: If you are on a boat with a ball that has a mass and that ball was threw into the water and it submerged, what would happen to the water level, will it rise, will it fall or will it stay the same
First start by drawing a diagram of the scenario, let the mass of the boat be (M) and the mass of the ball be (m)
Vdisp(1) is volume of the water displaced before the ball was threw in to the water, Vdisp(2) is volume of the water displaced after the ball was threw in to the water, ρw is the density of the water, ρb is the density of the ball
To know if there was a change in the water lever you have to take Vdisp(1) - Vdisp(2)
• From the question it says the ball submerged, therefore its density is greater than the density of the water. Because that is true that means Vdisp(1) - Vdisp(2) is positive. Z1 is water height before the ball submerge while Z2 is after the ball submerge, A is just Area.
• That means the water lever will fall.
3) If you shorten a spring, how will if effect it stiffness
• First know that the equation of a spring is F = -kx, stiffness will be (k) while length will be (x)
• From the formula k will be F/-x, that means if you shorten the spring it will increase its stiffness.
4) Compare the Stress-Strain Curves of Steel and Aluminum
• First start by drawing your axes, let stress be the y-axis and strain the x-axis
• Let’s start by sketching aluminum curve, in the stress-strain curve we have elastic region and we have plastic region, in the elastic region any deformation experienced by the material will return to its original shape and it also were you will get the young’s modulus(E). In the plastic region deformed materials can never return to their original shape, here you will also get the ultimate strength and point of fracture. At the yield point is when the material changes from elastic deformation to plastic deformation, from the yield point to the point of ultimate strength the material exhibits strain hardening and from the point of ultimate strength to the point of fracture the material exhibits necking. (Note: strain hardening is the desirable or undesirable hardening of the material, while necking is when a large amounts of strain localize disproportionately in a small region of the material causing a decrease in the cross-sectional area of that region.)
• Steel goes through the same process as aluminum except the elastic region is much steeper than aluminum and it is a stronger material overall, one key difference between aluminum and steel is that steel exhibits something called yield point phenomenon where you have two different yield points (that's because of certain interstitial atoms within the microstructure of steel that allows for this to happen)
5) How would the back of an Iphone be manufactured?
• For the body the multiple process you can use such as; CNC machining, casting or milling, milling is more important at the camera because that requires more precision.
• Holes for the speaker you can use CNC machining or drilling.
• Shine at back you can use grinding or anodizing process.
• These are some ways to use to manufaction an Iphone, ofcourse they are more ways to manufacture an Iphone but this is just a general run-down of some of the processes
6) What are the differences between Steel and aluminum
• Steel is heavier than aluminum because steel have a higher density.
• Steel is magnetic metal while aluminum is a non-magnetic metal
• Steel has a higher melting point than aluminum
• Steel is harder than aluminum
@@ravijain7024 Steal is tougher than Aluminum, therefore Aluminum will experience more deformation
Tamer and Tauseen to the rescue again! 👌🏽🔥
What a conceptual question all are very basic questions! ✨
Shortening a spring doesn't refer to reducing the x value (displacement from the equilibrium position). It's referring directly to the factors that affect the k value. One of those factors is n, which is the number of coils (this is directly proportional to spring length). You can look up the equation for k. Shortening the spring does increase stiffness, so your final answer is correct :)
Hmm that’s a good point, I’ll look into that...thanks for sharing :)
@@TamerShaheen this channel has value
@@TamerShaheen man I am sad that I could not become engineer :(
@@masternobody1896 I don't think its too late. You can always study if you have the time. You can also make engineering a hobby. Basically, make things when you are free and for fun. Don't give up my friend!
There's a great answer on Physics Stack exchange .com:
k=Gd^4/8nD^3
where d is the wire diameter, D the coil diameter, n the number of active coils, and G the shear modulus. So if you cut it in half n→n/2 the spring constant doubles k→2k. The maximum length decreases of course and you get into the non-linear regime with less displacement.
may I ask if you'll do more of these technical questions?
Should do part2
Love this video Tamer! I was wondering where did you source your bullet point time stamps shown in the video from?
Real talk, his friend looks like the Desi/Arab version of The Weeknd. Ma sha Allah. Does anyone else see it?
Very nice video. Currently studying mech eng at Waterloo as well and Apple is the dream in Sha Allah.
Nice video man!! When are you going to make a day in a life video
In February
never interviewed as an intern but for fulltime they go way way way deeper into these questions.
Ya I made this video back when I was interviewing for Apple internships. After posting this video, I got to experience Apple full-time interviews and the level of detail and technical questions are tough.
@@TamerShaheen It will be great help if you can continue this series of interview questions for the Full time Job roles also.
@@arupdey897 full time they mostly won’t ask you textbook questions. Interviewers usually come up with their own questions, and they typically are something like :”I want something like this , how would you design it”. Then you are expected to explain your ideas. Usually there are no right or wrong but that how they evaluate your kills. The thing is interviews are not like taking a exam in school, doesn’t mean u answer everything right and you get the job. You can be an amazing junior engineer but if they thing it’s better to find someone more senior then they won’t move forward
Thanks guys. SpaceX asked me the rock in the rowboat question, LOL
Do a part 2,
HELP :( why do you use in the second exercise for the boat the density of water and for the ball the density of the ball?
With ms in mechanical engineering, can I work in apple as mechanical design engineer? What will be my job description in apple as mechanical engineer? Is electronics knowledge needed to work in apple ? Pls reply
Do they provide you with equations?
Nice
I asked many interviewrs about if they do technical questions during interview and none of them actually said yes, so this is honestly is kinda not accurate.
Bro we want interview questions for full-time engineering interviews.
With all these technical questions, I'm def not getting a job. This makes me realize that I just sat there in class just to pass & not understand the material🤦🏻♀️😩😫😫😫😫😫
It makes more sense as the years go by. Trust me, in first year, I was lost too on what I wanted to do in life and I couldn’t answer these questions. But, it just starts to make sense by your third year, plus u can always learn more in ur down time.
Can you talk more about computer science
Sure, I will. Do you have any specific questions?
Is doing computer science worth it. Like do you have a lot of time when majoring CS, how hard is all of the CS work
could the ball be somewhat submerged? like heavy enough not to be floating at the surface but light enough to not go to the sea bed?
That would have to play into temperature or some other external factor not accounted for in the problem. If so, then this solid is the same density as water
@@nocknock4832Not really, if you know the ratio of the amount submerged to the amount floating which you would have to know in this case, you can find the volume displaced that way.
You both are so cute
the boat solution was explained so terribly.. but thanks for the question anyway
Do you have answer to the balloon question? I’d love to know as I’m facing an interview next week
What balloon question are you referring to?
@@TamerShaheen there is a very weird question asked by Apple : the room is full of balloons after a bday party , tell me 20 different ways to get rid of them .
@@thakursaab4050 Just get the super monkey. Its quick and efficient. XD
@@thakursaab4050 It could be an add-on to the mass in the boat question. After you have determined the water level goes down when you release the rock, the interview asks: Is there anything you could release that would cause the water level to go up? (The answer being a balloon!)
In the cantilever beam deflection, I = Moment of Inertia , not area.
Overall great video. Do a part 2
Second moment of area ;)
Yeah, It's second moment of area. If it were moment of inertia, why is there no mass term, derpy-derp?
I though it this was a video about apple not how to solve complex problems
It is a video about Apple haha. All they ask in their interviews is these complex questions lol
@@TamerShaheen Thanks for this video! Definitely helps me prep for my interviews. You guys are awesome!
All stainless steels are NOT Magnetic. On your picture - you showed Aluminum and Stainless Steel as the comparison.
Stainless Steel alloys come in all varieties:
In order for stainless steel to be magnetic - it has to be either Ferritic or Martensitic - like most of the 400 Series Stainless Steels.
In most industries - the stainless steel alloy of choice is actually 304 or 316 - both of which are Austenitic. That is NON-Magnetic.
I have literally seen young engineers make this mistake in my industry - they automatically assume a part can't be stainless steel if it's not magnetic. That's false.
Love your profile pic. XD
Can't wait for the day when they send actual people to mars. :D
@@plasmawave2565 That would indeed be an epic day - perhaps - one of the most important days in humanities existance! I'm excited just thinking about it! It can't come any sooner!
@@EngineerHarrisI can't wait either! It's going to be really epic. It's one of the reasons I'm going to do Aerospace this year. Is so cool to know we're going to another freaking planet! What also excites me is the soon to be moon bases. Imagine looking at the moon and seeing city lights! Sooo awesome.
Crazy how these companies want to hire mindless robots that memorize this shit versus cognitive abilities or soft skills
Yeah, some of these questions they ask in job interviews are insane. Especially when the interview itself can already be stressful.