Sahil Gupta

Sahil is the CEO at Sawan Books. He pursued his Bachelor’s Degree in Bussiness from the University of Chicago, USA and currently working on his ultimate goal - ‘To see a book in every child’s hand.’ .

Why is it easy to erase off pencil-marks from paper but not ink-marks?

Paper is mostly manufactured with an even distribution of cellulose fibres with small pores. When we write in ink, it moves down into the pores of the paper, where it will remain to dry. To erase off ink-marks, it is difficult for the rubber to separate the intermolecular forces. Therefore, it has to be physically

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Why are sleeping people heavier to lift than the ones who are awake?

While one is asleep, one’s body-muscles become relaxed and lose all stiffness. When a sleeping body is picked up, its muscles do not assist in the lifting and we feel the entire weight, almost like ‘dead-weight’. ‘Dead-weight’ refers to the placement of the weight. When an awakened person is picked up, he adjusts his weight

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Why do some airports have unusually long runways?

Some airports are placed in locations with high altitudes/elevation with high ambient temperatures around. In these kinds of airports, take-offs become difficult because the low air density negatively affects the lift generated by the wings or the rotors of the airplane. This also affects and hampers with the performance of the aircraft engines, jeopardizing the

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Why don’t you need to put seatbelts while travelling in a bus?

The most important reason that differentiates safety of buses from that of other modes of transport is called ‘compartmentalization’. It is also the reason why there are no seatbelts on buses. In compartmentalization, the seats are placed very close to one another and covered with energy-absorbing pads. This makes the movement very minimal in case

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Why do our mouths literally ‘fall open’ when we are shocked?

Opening our mouths is the best and foremost method for drawing in a huge breath filled with oxygen. We need oxygen because it prepares our muscles to either fight or run away in a ‘flight or fight’ response. We have this response when we come across some trigger that invoke fear or surprise. When faced

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