KNOW WHY BOWLERS RUB BALL IN CRICKET MATCH !!

While watching cricket match you might have seen bowlers rub the ball often against their trousers. Have you even wondered why bowlers do so? We will discuss the reason behind the rubbing of ball in this article.

Actually, whenever you rub the ball, no umpire or match referee tells you anything. At the same time, if you violate the ICC rules while rubbing it, then you also have to pay its loss. Let us first tell you why the bowler does this. Whenever the ball is new, it falls straight, very little swing (out swing, in swing or reverse swing) is found. In such a situation, only the batsman gets the benefit which no bowler wants.

Bowlers try to make the ball shine and smooth mainly for making it to slip on the bat and make it possible to render the batsman out by catches at slips and by the wicket keeper. The smooth ball is also likely to misbehave while it is hit for a bigger shot and are caught anywhere in the field an on boundaries.

Now,let us understand the science behind this.

When bowler is rubbing one side of ball he is actually polishing or smoothening the surface of the ball. Other half of the ball remains as it is or more rough. When bowler throws the ball at high velocity, low pressure is created near smooth surface and high pressure area is created on rougher side. This pressure differential SWINGS ball in air.

To look at this aerodynamically, one must understand the concept of boundary layer formation and separation. Boundary Layer is a layer of fluid (in this case, Air) which tends to stick to the surface of the object (The ball) when the object tries to move through the fluid. The boundary layer does not cause any effect on the object’s flow through the fluid (except for resistance) until it separates. Boundary layer separation occurs when the flow velocity increases to such an extent that the pressure difference increases drastically in the flow direction. Boundary Layer separation causes formation of eddies which then resist the movement of the flowing object. The Boundary Layer formed on any surface can be either Laminar or Turbulent. 

In Laminar Flow, the flow of the fluid is in organised parallel lines. Whereas, the Turbulent Boundary Layer the fluid particles move in disorganized and intersecting paths.Therefore, ball is made rough so that turbulent boundary layer is formed which results in disorganized movement of ball.

In conclusion, we have seen that science behind rubbing the ball.Thank you reading the article.

KNOW WHY VENTILATIONS ARE PLACED AT TOP OF THE ROOF !

We see doors and windows in our room in daily life. They are placed in such a way that we can pass through them easily. But, when we see ventilation, they are always placed at the top of the room. Have you ever imagined why are they placed on the top, why not near the window? We will discuss why ventilations are placed on top of the roof in this article.

Ventilations are basically window like structure that is used to pull out hot air in a room. Ventilation moves outdoor air into a building or a room and distributes the air within the building or room. The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants from it.

Ventilators are kept at the top of the roof to pass the hot air inside a room to pass outwards. As hot air is lighter than cold air relatively, it goes up near the ceiling & passes through ventilators as a result cold air finds its way to come in to fill the room. Hence, this ensures a circulation of air inside a room. Also, ventilation at the top ensures an ample amount of sunlight to enter into the room.

During night time, ventilators allow the cold air to flow inside the room. It also secures the oxygen level in a crowded room by circulating air. 

Home ventilation is important to keep the house and its occupants healthy and comfortable. Ventilation is a key component to maintaining proper indoor air quality. Ventilation keeps air flowing through the home, eliminating contaminants, moisture buildup, and odors.

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KNOW WHY TRAIN ENGINES ARE NOT TURNED OFF AT PLATFORMS !

You might have noticed that diesel trains are never turned off. They are always left running when they are on platforms for 30 or 40 minutes. Have you ever wondered why would the railway department waste so much fuel if the train isn't moving! It seems a bit strange, right? We will discuss the reason behind this in this article.

1.) Every diesel engine has a battery and this battery is charged only when the engine is running, if this battery is not charged then the loco motive system of the train can fail. It takes about 20 minutes for the engine to restart when the red light comes on the way or if the diesel engine of the train is stopped for any reason. Apart from all this, a lot of diesel is required to start a diesel engine.

2.)If the engine is turned off for long periods of time, it takes another long span of time to repressurise (as compressors take power from the engine) the brake lines. Trains, being large and heavy, need the optimal brake line pressure for its efficient stopping. For obvious reasons, loco pilots never compromise on brake line pressure.

3.)If the engine hasn't been started since long (or, if the engine is cold), it takes quite an effort to restart it. Depending on the size and construction of the engine, it can take 10 to 20 minutes just to start it.

4.) In some countries a diesel locomotive also provide hotel load to the coaches powering the air-conditioners, lights and pantry.

5.)Diesel engines don't really use that much fuel when idling, especially compared to the potential problems caused by shutting them down, so the engines are left running unless the train is being berthed for the night.

Today's trains have ‘Auxillary Power Unit (APU)' in order to reduce the fuel consumption while idling. This is a separate system for powering all the electronics, and is also found in aeroplanes. APU can also help in reducing the emissions in diesel locomotives.

It is clear from above points that engine is not shut down to save diesel consumption. Now you know why the diesel engine of the train is not stopped. Let us tell you that in coming time we may not get to see the diesel engines of the train, because diesel engines are being tried to replaced with electricity and this will benefit both the railways and the environment.

Thank you for reading this article.