Mecânica e máquinas simples · GCSE Physics Buoyancy & Density
Simulador do princípio de Arquimedes
Simulador do princípio de Arquimedes e empuxo hidrostático: flutuação e peso aparente
- No navegador
- Sem cadastro
- Dedução ao vivo
- Modo projetor
- Folha de exercícios A4
Janela de simulação 3D● 60 FPS
Variáveis de controle do experimento
cm³
g/cm³
g/cm³
%
Deduções e métricas em tempo real
Empuxo F_emp
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Peso do objeto G
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Leitura da balança
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Volume deslocado
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Dedução de fórmulas em tempo real
Fórmula fundamental:
--Substituição de valores:
--Estado físico: --
Exemplos clássicos e armadilhas de exame
Worked Problem
Problema: A 500cm³ iron block is fully submerged in water (rho=1.0g/cm³) and in kerosene (rho=0.8g/cm³). Find buoyancy. (g=10N/kg)
Derivação passo a passo:
- 1) In water: F_buoy = 1000*10*5e-4 = 5N; 2) In kerosene: F_buoy = 800*10*5e-4 = 4N. Independent of iron density.
Worked Problem
Problema: An ice cube floats in a beaker of water. When melted, does the water level rise, fall, or stay unchanged?
Derivação passo a passo:
- Stays unchanged! While floating, V_disp = m_ice / rho_water. When melted, the resulting water volume is m_water / rho_water = V_disp, exactly filling the displaced cavity.
Folha de investigação em aula e exercícios
Q1. Variant 1: An ice cube floats in saltwater. Does the level rise, fall, or stay unchanged after melting?
Answer Key: Rises! Floating displacement V_disp = m / rho_salt < melted pure water volume V_melt = m / rho_water, raising liquid level.
Q2. Variant 2: How does a submarine control diving and surfacing?
Answer Key: By flooding or blowing water from ballast tanks, changing its own weight G while submerged volume V_disp and buoyancy remain constant.
Q3. Variant 3: An object weighs 8N in air and 5N when submerged in water. Determine volume and density. (g=10N/kg)
Answer Key: F_buoy = 8 - 5 = 3N. Volume V = 3 / (1000*10) = 3e-4 m³ = 300cm³. Density rho = 0.8 / 3e-4 ≈ 2667 kg/m³.
Perguntas frequentes e erros comuns
Do submerged objects resting on the bottom experience buoyancy?
Yes. As long as liquid contacts the bottom surface, upward hydrostatic pressure exceeds downward pressure. Buoyancy is zero only if the base is sealed to the bottom with no liquid underneath.
Does buoyancy increase as an object goes deeper?
No. Once fully submerged, displaced volume V_disp equals object volume V_obj and remains constant. While ambient pressure increases, the difference in pressure between top and bottom stays unchanged.
When a ship sails from river to sea, does buoyant force change?
No, buoyancy still equals the ship weight. But because seawater is denser, displaced volume decreases, causing the ship to float slightly higher.
Do hot air balloons use Archimedes principle?
Yes. Air is a fluid. Heating air inside reduces its density, making balloon gross weight less than the weight of displaced cool ambient air (F_buoy > G_total).