Tutor profile: Emmanuel F.
Subject: Physics (Heat Transfer)
James wakes up in the middle of the night only to realize his apartment was on fire. The only exit is through the living room, which is on fire. He decides to wet a blanket thoroughly with water, cover himself in the wet blanket and pass through the fire for the exit. How does this wetting of the blanket possibly reduce the risk of him getting caught on fire?
As the fire comes into contact with the blanket, the heat energy would first have to evaporate the water in the blanket, giving him time to escape without getting caught on fire.
Subject: Physics (Fluid Mechanics)
Moving away from the earth's surface through the atmosphere, the density and pressure of air reduces with increasing altitude, and the air gets thinner as altitude increases. For safety of air travel, airliners have a maximum cruising altitudes beyond which they are not to climb. Apart from oxygen depletion, and poor communication quality with control tower, what possible aerodynamic consideration could also be a reason for these maximum ceilings, especially for heavy airliners?
Airliners, and most aircraft, require air (pressure differentials on the wing surfaces) to generate and maintain lift. As the airlines climb beyond these maximum ceiling altitudes, the air might become too thin for the aircraft to maintain lift.
A farmer who lives in a village, and drives his old pickup mostly on the untarred and bumpy road network connecting farming villages and market towns likes to keep his tires a bit under inflated. What benefit, if any at all, could he derive from this?
Dangerously low tire pressure levels could affect braking and steering negatively, and even cause premature wear, not to mention blowouts on tarred roads under hot conditions. However, a tire that is a bit under inflated is more 'compressible and malleable' than at its optimum pressure. On a bumpy road, this helps cushion the pickup from some of the shocks the farmer would have otherwise experienced, giving him a smoother ride on such roads.
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