engleski 2. zadatak, 2nd international young naturalists’ tournament

7/26/2019 Engleski 2. Zadatak, 2nd International Young Naturalists Tournament

1/8

INTERNATIONALYOUNG

NATURALISTSTOURNAMENT

2. Potatoes

Serbian team

Regional Center or Talente! Yo"t#


2/8

2nd problem, Potatoes

A classic board, as understood by carpenters, is arectangular parallelepiped with signifcantly varied

linear dimensions (length>width>thickness). They callsuch a parallelepiped a bar i width and thickness arecomparable. ! all three dimensions are comparable,they call it a cube. "hen a homogenous board #oats on

the water surace, its biggest ace is hori$ontal. A board%knows& perectly this rule and always %abides& to it.'ut or a bar the rule becomes ambiguous and itsbehavior is determined by ratio o its density to water

density. or a cube, it is even more %ambiguous& in thisregard. se potatoes or an e*perimental investigationo #oating bodies o di+erent shape. egulate thedensity ratio through adding salt to water. !nvestigatethe di+erent ways o how bodies o various shapes can#oat.


3/8

-omogeneous rectangular body shapeplaced in a container flled with liuid, cansink, #oat in the liuid or rise to the surace.

"hich o these three outcomes will occur,depending on the thrust orce and weight.

Thrust is directly proportional to the density

o the liuid, the volume submerged bodyand the orce o gravity.


4/8

! the thrust orce is eual to the weighto the body, the body will #oat in the

liuid. ! the thrust orce is greater than the

weight o the body, the body will #oat onthe surace o the liuid.

! thrust orce is less than the weight othe body, the body will sink.

/hanging the density o the liuid, we

change the thrust orce.


5/8

loating bodies o di+erent shape and si$e are maderom potatoes.

The bodies were divided into our groups and marked

with di+erent numbers. The frst group consists the bodies orm o a cube o

di+erent si$es (0,2,1). The second group consists bodies, various

dimensions, shaped like cuboid, in which the lengthis not substantially di+erent rom the width andheight (,3,4).

!n the third group are cuboid bodies, variousdimensions, in which the width and height are eual(5,6,7).

The ourth group includes a cuboid bodies, odi+erent dimensions, in which the height issubstantially less than the width and the length obody (08,00,02).


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9ach o these bodies, soaked in plainwater, will sink.

Adding salt, we have increased thedensity o water.

Ater adding the salt, body #oats on the

surace o the water, due to increasedthrust orce.


7/8

/ube shaped bodies were, ater addingsalt to the water, #oating on the water

surace. The same thing happened with the

bodies cuboid shape.


8/8

/uboid shaped bodies #oated on thesurace o the water, so the largest side

was parallel to the water surace.

engleski 2. zadatak, 2nd international young naturalists’ tournament

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