Presión de fluídos: problemas e solucións

1.

AA aceleración da gravidade é de 10 N/kg. A superficie do peixe presionado pola auga que está enriba del é de 6 cm²Determina a forza da auga sobre os peixes que actúa sobre eles.

Coñecido:

Aceleración debida á gravidade (g) = 10 N/kg

Surface area of fish (A) = 6 cm² = 6 x 10^-4 m²

Densidade of water = 1 gram/cm³ = 1 (10^-3 kg) / 10^-6 m³ = 10³ kg / m³ = 1000 kg / m³

Height of water = 100 cm – 15 cm = 85 cm = 85 x 10^-2 metros

Buscase: Force of the water above fish that acts on fish

Solución:

Ecuación de presión:

P = F / A

F = P A

F = ρ g h A

F = (1000)(10)(85 x 10^-2)(6 x 10^-4 m²)

F = (10⁴)(510 x 10^-6)

F = 510 x 10^-2

F = 5.1 Newtons

2. The normal pressure of blood is 80 mm hg to 120 mm hg. This value is equal to…

A. 80 Pascal to 120 Pascal

B. 800 Pascal to 1200 Pascal

C. 10256 Pascal to 17589 Pascal

D. 10526 Pascal to 15789 Pascal

Coñecido:

The normal pressure of blood = 80 mm Hg – 120 mm Hg

Quería: This value is equal to… Pascal

Solución:

The height of mercury in a barometer (above the surface of the sea) = 760 mm Hg

Pressure of air (above the surface of sea) = 1 atm = 1.0 x 10⁵ Pascal

1 mm Hg = ……. Pascal?

80 mm Hg = 80 x 131.58 Pascal = 10,526 Pascal

120 mm Hg = 120 x 131.58 Pascal = 15,789 Pascal

A resposta correcta é D.

3. Above the surface of the sea, the height of mercury in a barometer is 760 mm. If at a place, the height of mercury in a barometer is 700 mm. Determine the pressure of air at that place.

Coñecido:

The height of mercury in a barometer (above the surface of the sea) = 760 mm Hg

Pressure of air (above the surface of sea) = 1 atm = 1,013 x 10⁵ Pascal

Quería: Determine the pressure of air if the height of mercury is 700 mm

Solución:

760 mm Hg = 1.013 x 10⁵ Pascal

700 mm Hg = ……… Pascal?