5 1 density and pressure

Density is defined as the mass per unit volume of a material. It describes how much mass is contained in a given volume.

False. Objects made from high-density materials typically have a high mass.

The equation for density is Where:

The units for density are grams per cubic centimetre (g/cm³) when mass is measured in grams (g) and volume in cubic centimetres (cm³).

Gases are generally less dense than solids because the molecules in a gas are more spread out over a larger volume.

True. Density is a scalar quantity.

Volume is the amount of space occupied by an object in three-dimensional space.

The equation used to calculate the volume of an object is Where:

The object on the right is more dense because the particles are packed more closely together.

The aim of the core practical on measuring the density of regularly shaped objects is to determine the density by measuring the object dimensions

Density is the mass per unit volume of a substance.

A digital balance measures the mass of objects.

The independent variable in the core practical on measuring the density of regularly shaped objects is the type of shape/volume.

True. A Vernier caliper measures objects up to 0.01 mm in diameter.

A displacement eureka can is used to measure water displacement from irregularly shaped objects.

The density of a liquid can be determined by measuring its mass and volume, then using the equation for density.

The resolution of a digital balance is 0.01 g.

The displacement technique is used to determine the density of irregularly shaped objects.

Pressure is defined as the concentration of a force or the force per unit area.

The equation for pressure, force and area is Where:

True. Pressure is measured in pascals (Pa).

A force applied over a large area will result in a small pressure, and vice versa.

False. A high-heeled shoe produces a higher pressure on the ground than a flat-soled shoe when worn by the same person. This is because the same force is applied over a smaller surface area.

Tractors need large tyres to spread their weight over a large area to reduce the pressure they exert on the ground. This prevents them from sinking into the mud.

When a force is applied to the nail, it pierces and enters the wall. This is because the applied force is concentrated at the sharp pointed end, which produces a large pressure over a small area.

True. The area used in calculating the pressure should always be the cross-sectional area of the object. This is the area which is perpendicular (90 degrees) to the applied force.

The pressure applied by the grey face of the box onto the table is 4 Pa.

A fluid is either a liquid or a gas.

When an object is suspended in a liquid, it exerts pressure evenly across the whole surface of the object and in all directions. This pressure creates a force which acts at 90 degrees (right angles) to each surface.

The pressure of a liquid increases with both increased depth and increased density of the liquid.

False. The force created by pressure in a liquid is exerted evenly across the whole surface of an object.

The equation for the pressure difference of an object in a fluid is Where:

In the pressure equation for liquids represents the change in pressure in pascals (Pa).

in the pressure equation for liquids stands for the density of the liquid, measured in kilograms per metre cubed (kg/m³).

The depth of water in a swimming pool can be calculated using the pressure equation: The quantities needed to calculate depth are:

The property of pressure in a liquid demonstrated in the diagram is that pressure increases with depth.