LAB VIVA/INTERVIEW QUESTIONS OF THERMODYNAMICS !!

LAB VIVA/INTERVIEW QUESTIONS OF THERMODYNAMICS :

1. A quantity of matter of fixed mass and identity which is bounded by a closed surface. 

2. An enclosure which permits thermal interaction. 

3. An enclosure which prevents thermal interaction.

4. A system in which all the measurable variables have the same value as they had inside an enclosure after a long time, irrespective of the interaction that may have taken place. 

5. A region of interest, that is involved in the analysis.

 6. Any change of state occurring in a system. 

7. A region in space or control volume or quantity of matter upon which attention is focussed for study. 

8. A change of state which occurs while the system is adiabatically enclosed. 

9. Any observable characteristic of the system. 

10. A type of reversible process, characterized by the fact that the system is at each instant arbitrarily close to equilibrium. 

11. A study of the transfer and conversion of energy. 

12. If a thermodynamic system undergoes an adiabatic process, the net amount of work performed by it depends only on its initial and final states, and not on the sequence of intermediate state or path. 

13. Depends solely upon the state of the system and not upon how that state was reached. 

14. A change in the state of a system which occurs without any work being done. 

15. It is impossible to construct a device which, working in a complete cycle, will produce no other effect than the transfer of a quantity of heat from a cooler to a hotter body. 

16. Two states of two systems characterized by an absence of heat flow even when there is no adiabatic wall between them.

17. The loci of points corresponding to states of the same temperature.

18. A system going through some process whose initial and final states are the same. 

19. A system which exchanges heat and work with its surroundings while operating in a cyclic process. 

20. A hypothetical machine whose operation would violate the laws of thermodynamics.

ANSWERS:

1. system 2. diathermic 3. adiabatic 4. equilibrium state 5. system 6. process 7. thermodynamic system 8. adiabatic process 9. property 10. quasistatic 11. thermodynamics 12. first law of thermodynamics 13. property 14. free motion 15. Clausius statement 16. thermal equilibrium 17. isotherms 18. cycle 19. thermodynamic machine 20. perpetual-motion machine

AFTER-MARKET ABS !! ARE THEY WORTH ??

ABS which simply means Anti-Locking Braking System prevents the rear or the front wheel or both in some case from locking up which if fails, ends in a disaster.

In technical terms,Anti-locking Braking System, is a complex technology in a motorcycle or a car that can help reduce the speed or stop the vehicle in an emergency situation without locking either of the two wheels or even all the four in case of cars. This is achieved by using speed sensors that is attached to the wheels that continuously monitor the wheel rotation speed and sends the data to the braking ECU which is in turn connected to the hydraulic unit that adjusts the hydraulic pressure of the brake fluid inside accordingly. In an emergency braking situation which is otherwise panic braking, one can be confident that the wheels wouldn’t lock up giving the rider a taste of the tarmac.

Can ABS System Purchased separately (After-market ABS)?

The answer is YES. But there are certain hitches in that too! You’ll have to figure out a way to calibrate the aftermarket ABS to your specific car/motorcycle. You must also understand that automakers spend thousands of hours testing and calibrating a car/motorcycle fitted with ABS, in order to fine-tune its working in real-world conditions. Obviously, this isn’t something that’s feasible for most owners. This is also a reason why after-market ABS systems, though available, are unpopular. Also after-market ABS are costly for example, Bosch makes an aftermarket ABS that costs a whopping Rs. 6 lakhs! 

It’s better to buy a motorcycle that has a factory fitted ABS system which would have been tested rigorously by the motorcycle manufacturer as an integrated part of the motorcycle itself.

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WHY MODERN ENGINES USE FORGED PISTON? CHECK OUT THE ANSWER !!

Now-a-days forged pistons are used by most of high end vehicles.The main characteristic that makes forged pistons excel in high performance applications is strength and durability. 

The high silicon content of cast pistons makes them brittle compared to forged pistons. Silicon gives the metal lubricity and is mixed in the alloy to limit heat expansion. This is primarily the reason why cast pistons require careful handling. 

Mild shock applied to it may cause the material to break. The process of forging compresses the molecules inside the alloy, which results in a denser surface area compared to a cast piston.

The Difference:

The difference between a normal or cast piston and a forged piston is the manufacturing technique. Traditional cast pistons are considered good enough by most engine manufactures when it comes to stock setups, and suffer no drawback in terms of compression and service life. The cast piston is most common on all mass-produced engines, because the casting process of making this type of piston presents a low cost opportunity to the manufacturer.

Forged pistons employ a single lump of billet alloy which is stamped by the use of a die. The shape of the die determines the size and shape of the piston.Forged pistons are also easy to manufacture as there is no need for big, heavy and expensive casting equipment as employed in the manufacture of cast pistons.