20 + Interview Questions in Emission Control Methods in Automobile Engineering Page 1 InterviewSolution

1.	If the traction resistance is equal to the total running resistance, then which of the following will happen?(a) The vehicle will accelerate(b) The vehicle will decelerate(c) The vehicle will run at a constant velocity(d) The vehicle will come to restThis question was posed to me in an interview for internship.I need to ask this question from Vehicles and Powertrain in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The correct option is (c) The vehicle will run at a constant velocity Explanation: FTRACTION = Frunning (GIVEN).Frunning = Frolling + Faerodynamic and FNET = Ftraction – (Frolling + Faerodynamic). Fnet = Ftraction – Frunning = 0 N = mvehicle * avehicle ⇒ avehicle = 0 ⇒ Vvehicle = constant. THEREFORE the vehicle will run at a constant velocity.

Discussion

2.	If Frolling = 150 N, Faerodynamic = 400 N, Ftraction = 600 N, Fgradient = 0 N, what is the net force acting on the vehicle?(a) 100 N(b) 50 N(c) 550 N(d) 750 NThe question was posed to me in exam.This intriguing question comes from Vehicles and Powertrain topic in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct CHOICE is (B) 50 N Best EXPLANATION: FNET = Ftraction – Frolling – Faerodynamic – Fgradient = 600 – 150 – 400 – 0 =50 N.

Discussion

3.	What will happen if the vehicle is made 50% heavier, but all other parameters remain the same?(a) The running resistance will decrease(b) The running resistance will increase(c) The running resistance will remain the same(d) The aerodynamic resistance will increase by a factor of 1.5 squaredThis question was addressed to me in homework.I would like to ask this question from Vehicles and Powertrain in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Right option is (b) The running resistance will increase Explanation: Frunning = Frolling + Faerodynamic = (μk * mvehicle * g) + (0.5 * ρ * Cdrag * Afront * V^2). The running resistance is the SUM of ROLLING and aerodynamic resistance. Running resistance is DIRECTLY proportional to the MASS of the VEHICLE. As the mass of vehicle increases rolling resistance increases and thus, the running resistance increases. The aerodynamic resistance is independent of the vehicle mass.

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4.	Which one of the curves below represents a road gradient of 10%, if the mass of the vehicle is 1 ton?(a) B(b) A(c) D(d) CI got this question during an interview.This is a very interesting question from Vehicles and Powertrain topic in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The correct OPTION is (a) B The best explanation: Fgradient = mvehicle * g * SIN (α). For SMALL angles α, sin (α) = α = G. At G = 10%, sin (α) = 0.1 = α. Hence Fgradient = 1000 * 9.81 * 0.1 = 981 N. Using G = 0% curve as base curve and at speed = 0 Kmph, curve B is higher than the G = 0% curve across the full speed RANGE.

Discussion

5.	Suppose the vehicle is running at a constant speed on the flat road with rolling resistance = 100 N and aerodynamic resistance = 100 N, what is the traction force required?(a) 100 N(b) 0 N(c) 200 N(d) 50 NThe question was posed to me in an interview for internship.The query is from Vehicles and Powertrain topic in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct choice is (C) 200 N For explanation I would say: FNET = Ftraction – Frolling – Faerodynamic – Fgradient = 0 N (constant speed). Flat ROAD ⇒ Fgradient = 0. HENCE Ftraction = Frolling + Faerodynamic + Fgradient = 100 + 100 + 0 = 200 N.

Discussion

6.	What will happen if the traction force is negative?(a) The vehicle will accelerate(b) The vehicle will decelerate(c) The vehicle will first accelerate and then decelerate(d) The vehicle will run at a constant speedThis question was posed to me in an online quiz.This interesting question is from Vehicles and Powertrain in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The correct CHOICE is (b) The VEHICLE will DECELERATE To elaborate: Fnet = mvehicle* avehicle = FTRACTION – Frolling – Faerodynamic. If the Ftractionis negative, then Fnet will be more negative ⇒ avehicle is negative. Therefore the vehicle will decelerate.

Discussion

7.	Three-way catalytic converters reduce the emission of CO, HC, and soot.(a) True(b) FalseThe question was asked in final exam.Origin of the question is Engine Emissions in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct answer is (b) False To explain I WOULD say: Three-way CATALYTIC converters reduce the emission of CO, NOX, and HC. They are chambers contain catalytic material. It promotes the OXIDATION of the emission contained in the exhaust flow.

Discussion

8.	What is running resistance of the vehicle?(a) Rolling resistance(b) Aerodynamic resistance(c) Sum of rolling and aerodynamic resistance(d) Traction forceI had been asked this question in an online interview.This intriguing question originated from Vehicles and Powertrain in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct option is (c) Sum of rolling and AERODYNAMIC resistance The explanation is: Running resistance is the sum of rolling and aerodynamic resistance. Frunning = Frolling + F aerodynamic = (μk * mvehicle * g) + (0.5 * ρ * Cdrag * Afront * V^2). It is the resistance that will AFFECT when the VEHICLE is running. Running resistance is directly proportional to the mass of the vehicle, frontal area, and velocity. Increasing any of the above parameters will increase running resistance. Tractive force is the effort from the powertrain. Rolling resistance is the frictional resistance that wheels have to OVERCOME. Aerodynamic resistance is the drag force acting against the motion of the vehicle.

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9.	What can be reduced by using exhaust gas recirculation (EGR) effectively?(a) CO(b) NOx(c) HC(d) CO and HCI have been asked this question in class test.This question is from Engine Emissions in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct option is (b) NOx The explanation is: The most EFFECTIVE WAY of reducing NOx emission is to hold COMBUSTION CHAMBER TEMPERATURES down. Using this also reduces the thermal efficiency of the engine.

Discussion

10.	Which of the following cannot be reduced by thermal converters?(a) CO(b) HC(c) Soot(d) NOxThis question was addressed to me by my college professor while I was bunking the class.This question is from Engine Emissions topic in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Right choice is (d) NOx For explanation I WOULD SAY: NOx emission cannot be reduced using a THERMAL converter. Thermal converters are high-temperature chambers through which the exhaust gas flows.

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11.	Why is the fumigation technique used?(a) To control HC(b) To control NOx(c) To control CO(d) To control smokeI got this question in semester exam.This interesting question is from Engine Emissions topic in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Correct choice is (d) To CONTROL smoke For explanation I would say: The fumigation TECHNIQUE is used to control smoke. Fumigation is injecting gaseous or liquid fuel into the intake of air STEAM of CI engines. There are TWO types of smoke: hot smoke and COLD smoke.

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12.	For what purpose is the Rhodium used?(a) To reduce CO and HC(b) To reduce NOx(c) To reduce CO(d) To reduce HCThe question was posed to me in quiz.This intriguing question comes from Engine Emissions in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» CORRECT answer is (b) To reduce NOX Explanation: Rhodium is USED to reduce NOx. It is used to clean VEHICLE emission. It is mixed with the other two metals – platinum and PALLADIUM.

Discussion

13.	During which condition of the vehicle does NOx emission in SI engine will be lowest?(a) Cruising(b) Idling(c) Accelerating(d) DeceleratingThis question was posed to me in an interview for job.My question comes from Engine Emissions in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» CORRECT OPTION is (b) Idling For explanation: NOX emissions are lowest in SI engine during idling. NOx is created from nitrogen in the air. Nitrogen can ALSO be FOUND in fuel blends.

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14.	Which of the following causes the photochemical smog?(a) Excess O2(b) CO and CO2(c) Soot and particulate matter(d) NOx and HCThis question was posed to me in my homework.I would like to ask this question from Engine Emissions topic in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The CORRECT ANSWER is (d) NOx and HC Explanation: NOx is one of the primary causes of photochemical SMOG. This smog is formed by the photochemical reaction of AUTOMOBILE exhaust and atmospheric air in the presence of SUNLIGHT.

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15.	Which of the following is one of the major exhaust emissions from CI engines compared to SI engines?(a) Oxides of nitrogen(b) Particulates(c) CO and CO2(d) Unburnt hydrocarbonI got this question in exam.My query is from Engine Emissions in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» CORRECT ANSWER is (b) Particulates For explanation I WOULD say: Unburnt hydrocarbons are one of the major exhaust emissions from CI engines. The components in diesel FUEL have HIGHER molecular weight.

Discussion

16.	If the vehicle mass is 800 kg, what is the gradient force (approximate value in N) caused by the road gradient 10%?(a) 500 N(b) 600 N(c) 700 N(d) 800 NI got this question by my college director while I was bunking the class.I want to ask this question from Vehicles and Powertrain in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» CORRECT option is (d) 800 N To explain I would SAY: Fgradient = mvehicle * g * sin (α).For small ANGLE, sin (α) = α. HENCE, α = 10% = 0.1 rad. TAKING g = 10 m/s^2, Fgradient = 800100.1 = 800 N.

Discussion

17.	What does the blue smoke in diesel engine indicate?(a) Unburnt oil(b) HC(c) NOx(d) COThe question was posed to me in a job interview.The query is from Engine Emissions in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The CORRECT option is (a) UNBURNT oil For explanation: Blue smoke comes out from the EXHAUST when there is unburnt oil in the DIESEL engine. A very THIN layer of the oil gets deposited on the cylinder wall to provide the lubrication between the walls and the moving piston.

Discussion

18.	Why are lead compounds added in petrol?(a) Reduce knocking(b) Reduce HC emission(c) Reduce exhaust temperature(d) Increase power outputI had been asked this question during an online exam.I'm obligated to ask this question of Engine Emissions in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Right choice is (b) Reduce HC EMISSION For explanation: The lead compounds are added in petrol to reduce the HC emission. The additive TEL (TETRAETHYL Lead) was added to increase the OCTANE number. The resulting lead in the engine EXHAUST was a poisonous pollutant.

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19.	Suppose the road gradient is G = 10%. What is the corresponding angle (approximate value in radians)?(a) 5 rad(b) 0.1 rad(c) 1 rad(d) 10 radI have been asked this question during an online interview.This interesting question is from Vehicles and Powertrain in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» Right choice is (B) 0.1 RAD Explanation: G = tan (α). For SMALL angles α, tan (α) = α. Hence α = 10% = 0.1 rad. The corresponding angle for road GRADIENT G = 10% is 0.1 rad.

Discussion

20.	If the vehicle is running on the road having 10% gradient at a constant speed, then on flat road it will accelerate at approximately 1 m/s2 (All the parameters remain the same).(a) True(b) FalseI got this question in an international level competition.The origin of the question is Vehicles and Powertrain topic in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering
Answer» The CORRECT answer is (a) True The EXPLANATION is: F net = FTRACTION – Frolling – Faerodynamic – Fgradient. In CASE 1: Due to constant speed ⇒ avehicle = 0 ⇒ Fnet = 0 N and Ftraction = Frolling + Faerodynamic + F gradient. In case 2: Due to flat road, Fgradient = 0 N and Fnet = Ftraction – Frolling – Faerodynamic. As all parameter remain the same ⇒ Ftraction will be the same. Therefore Fnet = Fgradient. Fnet = mvehicle * avehicle = mvehicle * g * sin (α) = Fgrad. For small values, sin (α) = α. Therefore avehicle = g * α = 9.81 * 0.1 = 0.981 m/s^2 which is APPROXIMATELY 1 m/s^2.

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Explore topic-wise InterviewSolutions in .

Three-way catalytic converters reduce the emission of CO, HC, and soot.(a) True(b) FalseThe question was asked in final exam.Origin of the question is Engine Emissions in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering

What can be reduced by using exhaust gas recirculation (EGR) effectively?(a) CO(b) NOx(c) HC(d) CO and HCI have been asked this question in class test.This question is from Engine Emissions in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering

Why is the fumigation technique used?(a) To control HC(b) To control NOx(c) To control CO(d) To control smokeI got this question in semester exam.This interesting question is from Engine Emissions topic in division Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering

For what purpose is the Rhodium used?(a) To reduce CO and HC(b) To reduce NOx(c) To reduce CO(d) To reduce HCThe question was posed to me in quiz.This intriguing question comes from Engine Emissions in chapter Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering

What does the blue smoke in diesel engine indicate?(a) Unburnt oil(b) HC(c) NOx(d) COThe question was posed to me in a job interview.The query is from Engine Emissions in section Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering