Compressed air coming out from a punctured football
A. Becomes hotter
B. Becomes cooler
C. Remains at the same temperature
D. May become hotter or cooler depending upon the humidity of the surrounding air
Answer: Option B
This Question Belongs to Mechanical Engineering >> Engineering Thermodynamics
Join The Discussion
Comments ( 2 )
Addition of heat at constant pressure to a gas results in
A. Raising its temperature
B. Raising its pressure
C. Raising its volume
D. Raising its temperature and doing external work
Which of the following items is not a path function?
A. Heat
B. Work
C. Kinetic energy
D. Thermal conductivity
An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is
A. Feasible
B. Impossible
C. Possible
D. Possible, but with lot of sophistications
The absolute zero pressure can be attained at a temperature of
A. 0°C
B. -273°C
C. 273 K
D. None of these
It is due to throttling..
In ideal gases temp is const after throttling ..
However ..in this case , air becomes cooler after throttling ..
When air is coming out of punctured football, puncture acts like a nozzle. when fluid is passed through nozzle, velocity increases and pressure decreases, resulting in decrease of temperature.
You can observe this phenomenon by keeping your hand near mouth and blowing.
Case 1. Keep your mouth wide open and blow the air
Case 2. Open your mouth little and blow.
In case 2, you will feel air much cool. Here mouth is acting like a nozzle.