• What is the thing(s) that only Mechanical Engineers know?

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• We know that AC isn't just about making coldness, it can be used to make a room hot too because it is a Air conditioning. You can also use an AC as an improvised heater by turning it backwards, so it blows colder air out and hot air in but that would be far from efficient. Also, it adjusts the air velocity and the humidity.
• We know the reason behind the air conditioning system in ICU room is not just for luxury hospital but to cool the machinery also. Overheating the machinery can cause malfunctions.
• We know the reason behind why airplane windows always have round edges instead of square because sharp corner of square window is weakened by stress concentration.

• We know “why are tyres in black color ?” because of chemical compound carbon black is added in rubber which increases the strength and durability of tyres and carbon maintains the quality of tyres by protecting them from UV lights and ozone.

• We know “why are there stones alongside railway tracks ?” - The crushed stones are what are known as ballast. Their purpose is to hold the wooden cross ties in place, which in turn hold the rail in place. It is used to bear load from the rail road ties, to facilitate drainage of water & also to keep down vegetation that might interfere with the track.

• We know “why do some tuned car have very inclined tires ?” - The tilt of the wheel is know as camber angle. Tilting the wheel in that manner ( as shown in pic) is called negative camber. Mounting the wheel with a negative camber improves grip under hard cornering as it counteracts rolling.

• We also know “what does the green zone in speedometer indicate ?” - It is the zone where you will have more efficient speed where the fuel consumption is low.

• We know “why are roller bearings present in the bridge ?” - They are there to release any strain induced due to shrinkage and expansion of the bridge girder.( due to temperature, creep and shrinkage of concrete )

• We know that “It's more efficient to drive with Air conditioning on than window open above the speeds of about 55–60 kmph” because opening the window increase the air drag, and slows the car down so it needs more fuel to run.