Category: Objective Questions

Steam and Gas Turbines Multiple Choice Questions on “Carnot, Rankine and Reheat cycle”.

1. Carnot engine follows ____________
a) Isothermal process
b) Isoentropic process
c) Isothermal and Isoentropic process
d) None of the mentioned
Answer: c
Clarification: Carnot cycle process follows 4 process. They are
Isothermal heat addition
Reversible adiabatic expansion
Reversible isothermal compression
Reversible adiabatic heat rejection.

2. Clausius inequality is applied at _____________
a) reversible isothermal heat addition
b) reversible adiabatic expansion
c) reversible isothermal compression
d) reversible isothermal heat rejection
Answer: c
Clarification: In reversible adiabatic compression entropy is same as from reversible isothermal heat addition and this can be found out by clausius inequality.

3. During reversible adiabatic explansion and compression entropy doesnot change.
a) True
b) False
Answer: a
Clarification: Adiabatic process mean there is no heat transfer and if there is no heat transfer entropy doesnot change.

4. What happens if all the process in carnot cycle be reversed?
a) Works as heat engine
b) PMM1 occurs
c) Works as refrigerator
d) PMM2 occurs
Answer: c
Clarification: When all the process in carnot cycle be reversed heat is absorbed from the body and reduces the temperature of the body which means a refrigerator. When carnot cycle is not reversed it acts as a heat engine.

5. Working fluid of rankine cycle usually _____________
a) Water
b) Methane
c) Hard water
d) None of the mentioned
Answer: a
Clarification: Water is used as working fluid in rankine cycle.

6. Steam turbines work on __________
a) Rankine cycle
b) Carnot cycle
c) Dual cycle
d) None of the mentioned
Answer: a
Clarification: Rankine cycle is generally used where heat energy is to be converted in mechanical energy.

7. In non ideal rankine cycle the compression of pump and expansion of turbine is isoentropic.
a) True
b) False
Answer: b
Clarification: In general isoentropic cases are harder to occur and hence in rankine cycle they doesnot exist as isoentropic process.

8. What is the use of reheat cycle in steam turbines?
a) To remove the moisture from the steam
b) To increase the steam temperature
c) To increase steam pressure
d) None of the mentioned
Answer: a
Clarification: Reheat cycle is worked with rankine cycle to remove the moisture from the steam.

9. In rankine cycle with reheat how mny turbines work?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: One turbine is to produce work and the other turbine is to reheat.

10. Reheat temperatures are very close to ______ temperature.
a) inlet
b) outlet
c) intermediate
d) none of the mentioned
Answer: a
Clarification: After passing from the first turbine again the steam enters the boiler to raise their temperature close to the inlet temperature and then enters the low pressure turbine.

Steam and Gas Turbines Questions for entrance exams on “Requirements for Radial Equilibrium and Velocity Diagrams”.

1. For radial equilibrium axial flow is assumed.
a) True
b) False
Answer: b
Clarification: For radial equilibrium asymmetrical flow is assumed.

2. For radial equilibrium constant velocity is assumed.
a) True
b) False
Answer: a
Clarification: For radial equilibrium meridional velocity is assumed to be constant.

3. For simple radial equilibrium it is assumed that ______________
a) r*Vu = constant
b) r/Vu = constant
c) Vu/r = constant
d) None of the mentioned
Answer: a
Clarification: For a free vortex in a radial equilibrium it is assumed that the product of radius and velocity has remained as constant.

4. Secondary losses are caused due to _________
a) frictional forces
b) lift force induced in turbine
c) drag force induced by secondary force
d) none of the mentioned
Answer: c
Clarification: Secondary losses are caused due to drag forces induced by secondary forces.

5. For radial equilibrium it is assumed that viscosity is __________
a) high
b) negligible
c) low
d) none of the mentioned
Answer: b
Clarification: For radial equilibrium the flow is assumed to be asymmetrical and viscous forces are assumed to be negligible.

6. In radial equilibrium method blade force is assumed to be ____________
a) high
b) low
c) zero
d) none
Answer: c
Clarification: Blade forces are assumed to be zero in radial equilibrium.

7. For radial equilibrium it is assumed that heat transfer is ____________
a) zero
b) high
c) low
d) none
Answer: a
Clarification: For radial equilibrium it is assumed that the flow is non viscous flow and heat transfer is zero.

8. For radial equilibrium entropy term is _________
a) high
b) low
c) neglected
d) none of the mentioned
Answer: c
Clarification: For radial equilibrium method entropy term is neglected.

9. For radial equilibrium it is assumed that the steam lines are ___________ to the axis line.
a) perpendicular
b) parallel
c) inclined
d) none of the mentioned
Answer: b
Clarification: For radial equilibrium it is assumed that the steam lines are axis parallel and have no inclination.

10. For radial equilibrium friction is neglected.
a) True
b) False
Answer: a
Clarification: Friction is neglected in radial equilibrium.

Steam and Gas Turbines for entrance exams, answers/”>

Automobile Engineering Multiple Choice Questions & Answers on “Engine Valves and their Mechanisms”.

1. In a four stroke engine each cylinder has
a) One valve
b) Two valves
c) Three valves
d) Four valves
Answer: b
Clarification: A four stroke engine cylinder has one intake and one exhaust valve.

2. In a diesel engine the fuel injection pressure is in the range
a) 100 to 170 atm
b) 60 to 70 atm
c) 30 to 40 atm
d) 20 to 25 atm
Answer: a
Clarification: The pressure of fuel injection is very high for a diesel engine.

3. The valve is opened as the cam lobe on the cam raises the
a) Bearing
b) Piston
c) Valve lifter
d) Valve seat
Answer: c
Clarification: Valve opens when valve lifter is raised.

4. Exhaust valve temperature is about
a) 35 degree celsius
b) 100 degree celsius
c) 150 degree celsius
d) 500 degree celsius
Answer: d
Clarification: The temperature of the exhaust valve is of the order of 500 degree celsius.

5. The size of the engine intake valve is
a) Same as that of exhaust valve
b) Smaller than that of exhaust valve
c) Larger than that of exhaust valve
d) Does not depend upon the size of exhaust valve
Answer: b
Clarification: The exhaust valve is made bigger in size than the intake valve.

6. The device used to measure the clearance between the valve and tappet of an IC Engine is
a) Feeler gauge
b) Snap gauge
c) Slip gauge
d) Micrometer
Answer: a
Clarification: A Feeler gauge is used to measure the clearance.

7. The purpose of valve clearance is to
a) Allow the valve to expand
b) Allow the sliding of valve in the guide
c) Ensure that the valve closes fully
d) Ensure that the crankshaft is free to rotate
Answer: c
Clarification: Valve clearance ensures that valve closes completely.

8. The opening and closing of a valve is respectively done by
a) A cam and a spring
b) A spring and a cam
c) Gas pressure and cam
d) Cylinder vacuum and spring
Answer: a
Clarification: An engine valve is opened by a cam and closed by a spring.

9. On modern four stroke engines the exhaust valve opens just
a) Before TDC
b) After TDC
c) Before BDC
d) After BDC
Answer: c
Clarification: Exhaust valve opens before the piston reaches Bottom Dead Centre.

10. On modern four stroke engines the inlet valve opens just
a) Before TDC
b) After TDC
c) Before BDC
d) After BDC
Answer: a
Clarification: Inlet valve opens before the piston reaches Top Dead Centre.

11. A relief valve is fitted to the main oil gallery of an engine. The purpose of this valve is to
a) Limit the maximum oil pressure
b) Open when the oil is hot
c) Maintain the supply if the gallery becomes blocked
d) Stop the oil flow to the bearings
Answer: a relief valve limits the maximum oil pressure.

To practice all areas of Automobile Engineering, -automobile-engineering-questions-answers/”>

Automobile Engineering Multiple Choice Questions on “Vehicles and Powertrain”.

1. What is running resistance of the vehicle?
a) Rolling resistance
b) Aerodynamic resistance
c) Sum of rolling and aerodynamic resistance
d) Traction force
Answer: c
Clarification: Running resistance is the sum of rolling and aerodynamic resistance. F_running = F_rolling + F _aerodynamic = (μ_k * m_vehicle * g) + (0.5 * ρ * C_drag * A_front * V²). 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.

2. 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 rad
Answer: b
Clarification: 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.

3. 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 N
Answer: d
Clarification: F_gradient = m_vehicle * g * sin (α). For small angle, sin (α) = α. Hence, α = 10% = 0.1 rad. Taking g = 10 m/s², F_gradient = 800*10*0.1 = 800 N.

4. 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 speed
Answer: b
Clarification: F_net = m_vehicle* a_vehicle = F_traction – F_rolling – F_aerodynamic. If the F_tractionis negative, then F_net will be more negative ⇒ a_vehicle is negative. Therefore the vehicle will decelerate.

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 N
Answer: c
Clarification: F_net = F_traction – F_rolling – F_aerodynamic – F_gradient = 0 N (constant speed). Flat road ⇒ F_gradient = 0. Hence F_traction = F_rolling + F_aerodynamic + F_gradient = 100 + 100 + 0 = 200 N.

6. 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) C
Answer: a
Clarification: F_gradient = m_vehicle * g * sin (α). For small angles α, sin (α) = α = G. At G = 10%, sin (α) = 0.1 = α. Hence F_gradient = 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.

7. 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 squared
Answer: b
Clarification: F_running = F_rolling + F_aerodynamic = (μ_k * m_vehicle * g) + (0.5 * ρ * C_drag * A_front * V²). 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.

8. If F_rolling = 150 N, F_aerodynamic = 400 N, F_traction = 600 N, F_gradient = 0 N, what is the net force acting on the vehicle?
a) 100 N
b) 50 N
c) 550 N
d) 750 N
Answer: b
Clarification: F_net = F_traction – F_rolling – F_aerodynamic – F_gradient = 600 – 150 – 400 – 0 = 50 N.

9. 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 rest
Answer: c
Clarification: F_traction = F_running (given). F_running = F_rolling + F_aerodynamic and F_net = F_traction – (F_rolling + F_aerodynamic). F_net = F_traction – F_running = 0 N = m_vehicle * a_vehicle ⇒ a_vehicle = 0 ⇒ V_vehicle = constant. Therefore the vehicle will run at a constant velocity.

10. 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) False
Answer: a
Clarification: F net = F_traction – F_rolling – F_aerodynamic – F_gradient. In case 1: Due to constant speed ⇒ a_vehicle = 0 ⇒ F_net = 0 N and F_traction = F_rolling + F_aerodynamic + F _gradient. In case 2: Due to flat road, F_gradient = 0 N and F_net = F_traction – F_rolling – F_aerodynamic. As all parameter remain the same ⇒ F_traction will be the same. Therefore F_net = F_gradient. F_net = m_vehicle * a_vehicle = m_vehicle * g * sin (α) = F_grad. For small values, sin (α) = α. Therefore a_vehicle = g * α = 9.81 * 0.1 = 0.981 m/s² which is approximately 1 m/s².

Author engineerPosted on May 26, 2024May 26, 2024Categories Objective QuestionsLeave a comment on 250+ TOP MCQs on Vehicles and Powertrain and Answers