Предмет: Физика, автор: misutovavarvara

Глыба мрамора объёмом 1,5 м³ лежит на дне реки. Какую силу необходимо приложить, чтобы приподнять её в воде?

(Плотность тела ρглыбы=2700 кг/м³ и g=9,8 Н/кг).

Ответ (округли до десятых): необходимо приложить силу F≈
кН
Срочноооо

Ответы

Автор ответа: TheEvilGenius

Если тело лежит на дне, значит её вес превосходит силу Архимеда (силу выталкивания).

Вес тела: P = mg. m = ρ(тела) * V ==> P = ρ(тела) * V * g

Сила выталкивания (Архимеда): Fa = ρ(вода) * V * g

Чтобы приподнять тело, нам нужно уравновесить силы, простыми словами, помочь силе Архимеда вытолкнуть тело.

Сила: F = P - Fa = ρ(тела) * V * g - ρ(вода) * V * g = (ρ(тела) - ρ(вода)) * V * g

F = (2700 кг/м^3 - 1000 кг/м^3) * 1.5 м^3 * 9.8 Н/кг = 25 кН

Ответ: ≈ 25 кН

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