Fluids and Properties of Matter: SPI Physics

Formulas (2)

• Thrust, pressure and the pressure of a liquid column · Pressure
  $$P = \frac{F}{A} \qquad P_{\text{liquid}} = h\rho g \qquad 1\ \text{g/cm}^3 = 1000\ \text{kg/m}^3$$
• Pressure in a liquid depends only on depth · Pressure at a depth
  $$P = P_0 + h\rho g$$

Watch out for (4)

• Using g/cm³ in h ρ g
  → Thrust, pressure and the pressure of a liquid column
• Thinking a heavier-looking face presses harder
  → Thrust, pressure and the pressure of a liquid column
• Thinking the wall changes the pressure
  → Pressure in a liquid depends only on depth
• Thinking a wider vessel gives more pressure
  → Pressure in a liquid depends only on depth

Formulas (3)

• Density and relative density · Density and relative density
  $$\rho = \frac{m}{V} \qquad \text{relative density} = \frac{\rho_{\text{substance}}}{\rho_{\text{water}}}$$
• Buoyant force and the loss of weight in a liquid · Archimedes' principle
  $$F_B = \text{weight of liquid displaced} = V \rho_{\text{liquid}} g \qquad \text{apparent weight} = W - F_B$$
• Floating and the extra load a floating body can carry · Flotation
  $$V = \frac{m}{\rho} \qquad \text{greatest load (in kg)} = V \times 1000 - m \qquad \frac{\text{volume under water}}{\text{total volume}} = \frac{\rho_{\text{body}}}{\rho_{\text{water}}}$$

Watch out for (5)

• Giving relative density a unit
  → Density and relative density
• Forgetting the push back on the water
  → Buoyant force and the loss of weight in a liquid
• Thinking the buoyant force depends on the body's weight
  → Buoyant force and the loss of weight in a liquid
• Stopping at the total load
  → Floating and the extra load a floating body can carry
• Using the body's density for the water
  → Floating and the extra load a floating body can carry