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ASSUMPTIONS:Calculate the number of tennis balls that can fit in a Boeing 747
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The number of seats in a Boeing 747 are 500-600.Step 1: Calculating the total volume of Boeing 747
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Length of the plane is ~70m.Radius (in metre)3
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Assuming Beoing 747 as a cylinder, its radius is ~3m.Length (in metre)70
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Radius of a tennis ball is ~3.3 cm or 0.033m.Total Volume (πr²h) (in cubic metre)1978.2
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A boeing 747 has 60 rows and each row has 10 seats, 3-4-3 arrangement% of plane that will taper in the ends20%
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A chair can be looked at as a combination of 2 cuboids.Tapered area will form a cone which is one-third of cylinder130.5612
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Luggage area is considered empty.Occupied space by pantry/washrooms/overhead luggage etc40%
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Since the balls are spherical, they lead to wastage of space between 4 balls, therefore, they are treated as cubes and not spheresUnoccupied space (in cubic metre)1108.58328
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Step 2: Calculating the volume occupied by the objects inside Boeing 747
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Dividing the plane into 3 segments
CockpitSeatingLuggage
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AN OUT OF THE BOX TAKE% of area10%75%15%
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Being spherical, tennis balls cannot fill up all of the free volume inside the plane, and only a certain percentage, say 70-75%Volume (in cubic metre)110.858328831.43746166.287492
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Tapering of the fuselage and free volume inside empty fuel tanks can also be taken into account.Cockpit
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Objects inside the cockpitArea Occupied (%)Area Occupied (in fig.)
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2-3 seats for the pilot1516.6287492
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STRUCTUREInstrumentation Panel4549.8862476
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Total Volume of Boeing 747Free Volume (in cubic metre)44.3433312
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-Seating Area
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Volume occupied by the objects inside the planeCalculating the volume of one chair
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=DimensionsUpper partLower Part
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Volume that can be used to fit tennis ballsLength (in metre)10.6
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/Breadth (in metre)0.50.5
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Volume of a tennis ballWidth (in metre)0.10.1
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= Volume (in cubic metre)0.050.03
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Number of tennis balls that can fit inside a Boeing 747Percentage increase due to legs/handle etc20%
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Total Volume of a single chair (in cubic metre)0.096
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Total volume of all chairs
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SANITY CHECKNumber of rowsChairs per rowTotal no. of chairsTotal Volume
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Total Volume of a Boeing 747601060057.6
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1978.2Free Volume (in cubic metre)773.83746
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Free Volume in a Boeing 747Luggage Area
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984.4682832Total Volume = Total free Volume166.287492
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49.77%Step 3: Calculating total free volume in a Boeing 747
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Number of tennis balls that can fit inside a Boeing 747984.4682832
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3,424,285Step 4: Calculating the volume of a tennis ball
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Number of tennis balls per cubic metreRadius of a tennis ball (in metre)0.033
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3478Volume of a tennis ball = (2r)^30.000287496
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Step 5: Calculating the number of tennis balls that can fit inside a Boeing 747
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Total free volume of Boeing 747 (in cubic metre)984.4682832
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Total volume of 1 tennis ball (in cubic metre)0.000287496
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Number of tennis balls that can fit inside a Boeing 7473,424,285
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