Density & PressureEdexcel IGCSE Physics: Flashcards
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What is the equation for density?
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- What is the equation for density?
- ρ = m / V (density = mass / volume)
- What are the units of density?
- kilograms per metre cubed, kg/m³
- What is the equation for pressure?
- p = F / A (pressure = force / area)
- What are the units of pressure?
- Pascals, Pa
- How does the pressure at a point in a fluid at rest act?
- Equally in all directions.
- State the equation for pressure difference due to depth in a liquid.
- p = h × ρ × g, where h is depth, ρ is the liquid's density and g is gravitational field strength.
- Why does pressure in a liquid increase with depth?
- Because there is more liquid (and therefore more weight) above a deeper point, increasing the force per unit area.
- A block has mass 1.2 kg and volume 0.0006 m³. Calculate its density.
- ρ = m/V = 1.2 / 0.0006 = 2000 kg/m³
- A force of 40 N acts over an area of 0.05 m². Calculate the pressure.
- p = F/A = 40 / 0.05 = 800 Pa
- How can the volume of an irregular solid be measured for a density calculation?
- By displacement — measuring the volume of liquid displaced when the solid is fully submerged in a measuring cylinder.
- Why do snowshoes stop a person sinking into snow?
- They spread the person's weight over a much larger area, reducing the pressure exerted on the snow (p = F/A).
- Calculate the pressure due to 3 m of water (ρ = 1000 kg/m³, g = 10 N/kg).
- p = h × ρ × g = 3 × 1000 × 10 = 30,000 Pa