Mechanical Engineering core questions

MBA CAT 2022
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I think most of you guys would be searching for some good material of mech which is close to what we have studied in engg. I just found out this link . Its some kind of initiative taken by IITs to put all the lectures in written form over internet. almost all the main subjects are covered. The contents are good too. Make the most use of it !! especially during the office hrs


You will need to do a small registration and go to courses section on the page.

Njoy reading !!

The link is here
nptel.iitm.ac.in
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Tx Buddy this is great link

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somebody pleaseeee explain what is entropy?
i know it is introduced in the 2nd law of thermody but i dont undertand is it the available or useless energy? and does entropy of the universe always inc?

Someone give me an example of a ssytem in which the entropy of the sys dec???

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hey...for internal combustion engines, there's a book by Mathur & Sharma which gives almost all details....

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hi puys.........
There is a good website on Engg fundamentals that would be a useful ready reckoner to check on the following info.
1) Materials
2) Unit conversions
3) Understanding processes
4) Formulae of Heat Transfer, Fluid mechanics etc
5) Mathematics

The link to this website is
eFunda: The Ultimate Online Reference for Engineers

regds...
Bharath

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somebody pleaseeee explain what is entropy?
i know it is introduced in the 2nd law of thermody but i dont undertand is it the available or useless energy? and does entropy of the universe always inc?

Someone give me an example of a ssytem in which the entropy of the sys dec???



a simple example can be when the heat content of the system is decreasing
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Here are some of the questions I was asked at IIM K and IIM A interviews this month..

1) Three laws of thermodynamics
2) What is a transducer? What are bellows?
3) Iterative solution to e^x+sin x (?!?)
4) Newton's way of solving stuff or something like that
5) Why are laplace transforms used in math?
6) What are z-transforms? What are they used for?
7) Why are CFC's not used as refrigerants these days?
Is the temperature inside the aircraft increased or decreased artificially after takeoff? Why?
9) Why did the World Trade Center collapse one hour after the plane collided with it?
10) What is ammonia refrigeration?(or something like that)
11) What is entropy of a system?
12) Something on how does a four stroke engine work .....I can't remember the rest. I didn't know the answers to most of them, that's all I know

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Here are some of the questions I was asked at IIM K and IIM A interviews this month..

1) Three laws of thermodynamics
2) What is a transducer? What are bellows?
3) Iterative solution to e^x+sin x (?!?)
4) Newton's way of solving stuff or something like that
5) Why are laplace transforms used in math?
6) What are z-transforms? What are they used for?
7) Why are CFC's not used as refrigerants these days?
Is the temperature inside the aircraft increased or decreased artificially after takeoff? Why?
9) Why did the World Trade Center collapse one hour after the plane collided with it?
10) What is ammonia refrigeration?(or something like that)
11) What is entropy of a system?
12) Something on how does a four stroke engine work .....I can't remember the rest. I didn't know the answers to most of them, that's all I know


Dude Plzz mention your profile. ( work-ex/ fresher)

In question 3 you haven't mention the equation. You can't solve an expression. If the equation is e^x+sin x = 0 then its has infinite solutions.

Plzz explain question 4 in greater detail

try recalling the rest of the questions
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These questions were asked by Great Lakes people

1). What is the unit for pressure in layman terms? (pascal)

2). What are the ways of measuring pressure? (like U tube manometer etc.)

3). Bernoull's eq (total energy in stable, incompressible, non viscous fluid is constant)

4). Types of fluid system? (hydraulic press, accumulator, crane, lift, torque converter, gear wheel pump, air lift pump, coupling etc.)

5). Diffrence between refregeration & air conditioning

6). What is the difference between a compressor and a blower? (if mor & more pressure is delivered, it a called a compressor. If the pressure delivery is low, it is a blower. Blower can be called as a low pressure delivering compressor. Compressor can be called as a HJigh pressure delivering Blower/Fan)

7). How many types of turbines were given in your book? (Impulse, Reaction)

. Where hydraulic systems will be used in an aircraft?

The following question was asked at LIBA

1). What are the steps do you take before manufacturing a product
(planning, control, delivery)

@ IIT Kanpur

1). Draw a graph for y= e^(x) + e^ (-x) {we'll get a V shape, half V to the left of Y axis & Half V to the right. The graph meets Y axis at 2 units)

2). What is the difference between Mutually exclusive events & independent equations. Explain with an example?
(mutually exclusive events r the vents where occurenc of one event stops the other. Toss a coin. Head occurence stop the tail occurence.
Independent events happen without affecting each other. If u r to select a lady & gentle man from a group of 4 & 5 respectively, they are independnt. Selecting a man & Lady will not be dependant on each other. They r independent actions)

3). What changes do you make in an automobile engine if you want to use Bio-Diesel as the fuel?
(Coz bio diesel is viscous in nature, it must be chemically treated. Otherwise, it'll choke the fuel flowing lines & lead to incomplete burning. So, filters, lining of pipes, combustion wall material must be changed.

4). What is a differential?

@ SCMHRD

1). If a torous (round shaped ring) made of iron is dropped into hot water, O.D. increases. What happens to the inner diamater?
(decreases)

2). Why most of the manhole covers are made of circular shape than rectangular?.
(round shape takes lesser space than rectangular one for the same area)

@ SIOM

1). On what Newton's law, does jet engine works?
(newton's 3rd law of motion)

2). What is Newtons' third Law of motion?
(the jet comes with a fierce velocity, as a reaction, the jet plane moves)

@ IIT R

1). Will the cooling (because of water supply from a tank in a drip format) in a cooling chamber gets done by air current/water current? (it happens by bth of them)
(friends! this question is related to my work. Don't get confused. Assume that water is flowing thru grass, which is placed between two chambers. The cooling inside the chamber gets done by air/water curremt. That was the question was)
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Hey, this thread is gonna be really useful man...thanks.

Some of the questions thrown at me at IIM K:(8 months work ex for me)
1. Which car should i buy, petrol or diesel? (I said petrol for personal use and explained)
2. What is happening to the ozone layer?
CFC decomposing ozone to oxygen and destroying the ozone shield from UV.
3. Which is the silent refrigeration system?
Ammonia refrigeration or Bromine system. No moving parts, no compressor.
4. What is ASHRAE?
American Society of Heating, refrigeration and Air Conditioning engineers.
5. What is relative Humidity?

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Dude Plzz mention your profile. ( work-ex/ fresher)

In question 3 you haven't mention the equation. You can't solve an expression. If the equation is e^x+sin x = 0 then its has infinite solutions.

Plzz explain question 4 in greater detail

try recalling the rest of the questions



Hmm...profile Mech Engineer
One year work-ex at family manufacturing firm :satisfie:

In question 3, that was what they gave me, ok? How am I supposed to know what can be solved and what can't? :angry:

Question 4? It was something about math again, but I really don't recall what it was...as I said, how was I supposed to remember what I've never heard of before ??:angry::angry:
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Another good one

Q> What is a differential ? Does a Maruti 800 have a differential?

( Plzz answer the second part)

Q> Do Front wheel drives have differential and If yes what modificatiosn are made?

PS: People I guess we can make better use of this thread if we also post answers to the questions posted 😃

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Hmm...profile Mech Engineer
One year work-ex at family manufacturing firm :satisfie:

In question 3, that was what they gave me, ok? How am I supposed to know what can be solved and what can't? :angry:

lol


Question 4? It was something about math again, but I really don't recall what it was...as I said, how was I supposed to remember what I've never heard of before ??:angry::angry:

I guess they were talking about Newton_raphson method. it is an iterative process to solve complicated algebraic equations, like the one u stated in Q3(m not sure if the equation correct or not :)
for newton Raphson check this out: Newton-Raphson Method
but these are more electrical questions. Also the transformations - laplace n all are i think more applicable in electrical n electronics (DSP n all) for mechanical i think its limited merely to Control systems :
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2). Why most of the manhole covers are made of circular shape than rectangular?.
(round shape takes lesser space than rectangular one for the same area)

its a pretty interesting question. check this out for more
Manhole cover - Wikipedia, the free encyclopedia
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Another good one

Q> What is a differential ? Does a Maruti 800 have a differential?

( Plzz answer the second part)

Q> Do Front wheel drives have differential and If yes what modificatiosn are made?

PS: People I guess we can make better use of this thread if we also post answers to the questions posted :)

for differentials take a look at this
Howstuffworks "How Differentials Work"
as far as i know small cars at least do not have differentials. they can be found in lorries n trucks mostly. Had I been there @ the interview I wud hav said no for MAruti 800. not very sure what the right ans is 😐
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Here's whatever little i can answer:
Here are some of the questions I was asked at IIM K and IIM A interviews this month..

1) Three laws of thermodynamics
Zeroth Law - When two bodies are seperately in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other.
First law - Law of conservation of energy (energy can neither be created nor be destroyed. It can only be converted from one form to another or transferred from one body to another)
Q = W + U
Second law - Two statements
Kelvin Plank Statement - There is no process that, operating in a cycle, produces no other effect than the subtraction of a positive amount of heat from a reservoir and the production of an equal amount of work.
Claussius statement - No system can tranfer heat from a cold body to hot body without the application of external work.
(a more general representation is that flow of heat energy is always from hot to cold and entropy of the universe is always increasing)
Third Law - The entropy of a system approches zero when the temperature approaches absolute zero
2) What is a transducer? What are bellows?
3) Iterative solution to e^x+sin x (?!?)
4) Newton's way of solving stuff or something like that
5) Why are laplace transforms used in math?
Given a mathematical or functional description of an input or output to a system, the Laplace transform provides an alternative functional description of the system that makes it much more simple to analyse the behaviour of the system.
6) What are z-transforms? What are they used for?
7) Why are CFC's not used as refrigerants these days?
They lead to depletion of the ozone layer, therefore global warming
Is the temperature inside the aircraft increased or decreased artificially after takeoff? Why?
9) Why did the World Trade Center collapse one hour after the plane collided with it?
10) What is ammonia refrigeration?(or something like that)
Ammonia refrigeration is a vapor absorption refrigeration system.
Other conventional refrigeration systems are vapor compression refrigeration systems.
A vapor absorption system uses some heat source (usually industrial exhaust, boiler waste heat etc) from where energy is absorbed - therefore there is no need of a compressor(compressor increases pressure to help convert vaporised refrigerant back to liquid. In vapor absorption system heat source increases the temperature and therefore the pressure by keeping constant volume) Don't know more details.
11) What is entropy of a system?
Entropy is the degree of randomness or disorder in a system (at a molecular level).
In a system, it represents the amount of energy that is dispersed. e.g. all heat cannot be converted in to work (2nd law). The loss of heat is represented in the form of entropy.
dS = dQ/T
12) Something on how does a four stroke engine work .....I can't remember the rest. I didn't know the answers to most of them, that's all I know

Wish we had this thread earlier. At least I wouldn't have screwed my IIM-K interview then!
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sorry for the repeat post

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9) Why did the World Trade Center collapse one hour after the plane collided with it?
A) Its said that WTC didn't fall bcoz of Impact but bcoz of high temperature tsome of the beams melted and therefore the rest of the beams buckled. This explains the time lag.

PS: Its also said that the tower was designed in such a manner that if they fall ever they'll fall vertically ( which happened) so that adjacent buildings won't be affected. How is this possible ?
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Lapie Says
I was asked in my IIM-B interview that what is second law of thermodynamics and why is it important. I told them that second law of thermodynamics is that entropy of a system is always increasing and gave an example that we can find which way rxn will proceed by applying this law. Then they asked me is it valid when an ant is reproducing :wow: I still have no clue what they were trying to ask.

Well dug this ques out from the last page.
As far as entropy is concerned make sure while answering such questions make sure u r very specific n precise wid ur wordings. Here u missed out the term 'isolated'. the entropy of n isolated system always increases. if the system is not isolated then a certain process can can result in the decrease in the entropy of the system but in turn will increase the entropy of some other system(s) in such a way that the net effect is an increase in the entropy 😃 .
Now try answering the ant Q.
another interesting Q is 'since entropy always increases, so a manager doing work in his Org must also be increasing entropy hence the disorderliness. but that's not true...or is it?"
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Moving the thread to Prep Resources - that's the relevant section and moreover it might get lost in the CAT and Related Discussions section 😃