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Thermal Efficiency
Why the thermal efficiency of the engine decreases at part load?
kanthasami
- Jul 26th, 2009
There are always some mechanical losses in the engine while running. These losses are more or less same at all the speeds. When the speed decreases, the output will obviously decreases. But, the losses remain same. So, the overall efficiency also decrease.
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Gear Shifting Technique
In two wheeler the first gear are engaged in front shifting and remaining are engaged by back shifting of gear pedal, Why?
rakesh8014
- Jul 5th, 2010
It depends on design of gear box. It is not only 1st gear downward and others are upward always, it may be all gears towards down or towards up. The movement of gear lever engage different gears set of gears in different combination to get the required output.
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Strength of Oval Pipes
Why is the strength of oval pipes more than that with circular cross-section?
sunnyzafar
- Jul 4th, 2010
It is bcoz the value of section modulus of an ellipse is more than than of a circle. Hence using bending eqn, we can see that strength of oval pipe is more than circular pipe.
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Supercharging
What is mean by supercharging? How supercharging works in automobile?
sandeepfunky
- Jul 2nd, 2010
Super charging is a process in which compressed air is sent in to the engine cylinder, this is basically to increase the efficency of the engine, found mainly in diesel engines. The atmospheric air is...
sunil vishwakarma
- Jul 2nd, 2010
It is done to improve power obtained from engine. Idea behind it is that it could be done by increasing mass flow rate in engine cylinder, for that at initial stage dendity of charge is increase...
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Maximum Torque Produced
What is the meaning of maximum torque produced at a specified RPM?
sandeepfunky
- Jul 2nd, 2010
Torque can be defined as the energy used to rotate the body on its own axis. RPM is revolutions per minute. so the maximum torque attained in a particular RPM is the amount of force obtained to rotate a body attached to a fixed point.
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Gravitational Constant
The value of gravitational constant below see level at 4500m depth was found to be 9.8295m/s2 and this is maximum after that it decreases...What would be the value of the acceleration due to gravitation at the center of earth?
saurav_sammy
- Jun 20th, 2010
the gravitation constant again decreases as we go down the 4500m level below the sea level....
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Hydraulic Devices
What is an Hydraulic Device?
puneetrawat
- May 15th, 2010
Hydraullic devices are those which has oil as the working medium like hydraullic pumps.
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Surging and Choking
What is Surging and Choking?
r.mech
- May 8th, 2010
Due to increse of load on the compressor, mass flow rate is decresed. It would again tend to increase the mass flow rate. This unsteady to and fro motion of the fluid will cause pulsation in the compr...
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What is the meaning of refrigerant R21?
vrsaikumar
- Nov 4th, 2008
Dichlorofluoromethane or Freon 21 or R 21 is a halomethane or hydrochlorofluorocarbon. It is a colorless and odorless gas. Its critical point is at 178.5 ?C (451.7 K) and 517 MPa (51.7 bar). At tempe...
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What qualities do you think you can bring to mechanical engineering?
karthicvijay
- Apr 30th, 2010
1. Dont work hard but work smart.2. Bring out new innoviative ideas and share it with the world.3. Thinking different from others.4. Thirst for improvements.5. Always being sensitive.
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Bearing Clearances
How can we measure the industrial bearing clearances?
deepakargowda
- Apr 30th, 2010
We can measure bearing clearance with an outside micrometer and a dial bore gauge. We can also use plastiguage to measure the clearance.
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Pawl Ratchet
How do pawl and ratchet works?
vinoythomas
- Mar 15th, 2010
A ratchet mechanism is based on a wheel that has teeth cut out of it and a pawl that follows as the wheel turns
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Strenth of Material
A cantilever beam is loaded a point on its ends what will be the effect in shear force?
debesh220
- Mar 19th, 2010
Due to the shear force the bar shows a hogging type bending moment. The shear force diagram is like a triangle triangle in +ve direction.
d_tyro_22
- Jan 27th, 2010
Considering that the load is a concentrated vertical point-load, acting on the free end of the cantilever, reaction at the rigid end can be calculated, shear-force diagram and bending moment diagrams ...
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Turbine Efficiency
Will Bleeding of steam increases or decreases the efficiency of Turbine? Explain.
daruljothi
- Mar 12th, 2010
Bleed steam will increses the cycle efficiency of the unit because:1. It was takenout after considerable work output by HP turbine and 2. It can be used fully for heating of feed water and etc., incre...
technowiz
- Nov 1st, 2009
Bleed steam will increase the turbine efficiency this process is basicaly known as regeneration.
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Potential Voltage
Van de graff generator produces a voltage of 100,000 V but it does not harm us, where as, a 220V in wall outlet leads to death, Why?
chris10156
- Feb 17th, 2010
Voltage is not what kills someone, it is the amps.? 4-5 amps is usually all it takes for the heart to stop and to kill someone.? 100,000 volts would really sting, but it has an amperage so little that it does not harm anything.
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IC Engine Fuel
Explain the technical difference between LPG and Petrol in an IC engine?
mohsinali
- Feb 14th, 2010
System that handles Petrol & LPG is same but only basic difference is about fuel ratio.LPG doesn't require much effort in carburator to mix up the air because it require less air and that is because L...
ajay s joshilkar
- Dec 19th, 2009
LPG is already compressed petrol, therefore it doesn't Produce heat energy as the common petrol produce.
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Diesel Engine Efficiency
How to control air flow during suction stroke in Diesel engine, as excess Oxygen too reduces the efficiency of engine?
d_tyro_22
- Jan 27th, 2010
In my opinion, extent of opening or closing of the throttle valve is synchronised (during the designing of engine) according to the amount of air intake as per requirement.
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Bending Moment
What is the shape of bending moment diagram if a lone moment act at the mid point of the simply supported beam?
d_tyro_22
- Jan 27th, 2010
Expression for bending moment in terms of distance 'x' measured from left end:= -(Mx/L) ; 0<=x<L/2=-(Mx/L) + M ; L/2...
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Absolute Zero
Why is a temperature of absolute zero unachievable?
uthipse
- Jan 26th, 2010
Absolute zero of temperature may be defined as that temperature at which the rms velocities of the gas molecules become zero which is applicable only for ideal gas. Because practically, under extreme low temperature, gases change their stage to liquid much above the abs. temp. and then to solid.
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Gear Ratio
How gear ratio helps in power variation?
Nagesh M
- Jan 23rd, 2010
T1/T2=N2/N1, where T1 is no of teeth on driver; T2 is no of teeth on driven; N2 is speed of the driven gear & N1 is speed of the driver gear. The speed is inversly proportional to the torque developed by change of gears.
shefeerps
- Jan 22nd, 2010
N1/N2 = V1/V2where, N1=no. of teeth in 1st gearN2=no. of teeth in 2nd gearV1=velocity of 1st gearV2=velocity of 2nd gearVelocity varies with change in diameter of a rotating body system. Hence power.
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