Question 1: Define density in terms of mass and volume. State the SI units used for density.

Answer: Density is the mass of a substance per unit volume, expressed as kg/m^3.

Question 2: Explain why accurate measurement of mass and volume is important in determining density.

Answer: Accurate measurements are essential to obtain a correct value of density, as errors can significantly affect the result and lead to incorrect conclusions.

Question 1: List the main steps involved in measuring the density of an irregular solid using water displacement.

Answer: Weigh the object using a balance, record its mass; fill a measuring cylinder with water, record initial volume; submerge the object without splashing, record new water level; calculate volume displaced by the object; divide mass by volume to find density.

Question 2: Identify two variables that must be controlled during this experiment to ensure accurate results.

Answer: Temperature of water (to prevent expansion or contraction), and ensuring no water splashes out when submerging the object.

Question 3: State two safety precautions to consider when performing this practical.

Answer: Handle the water and equipment carefully to avoid spills; ensure the object and water are handled safely to prevent injury.

Question 1: A student measures the mass of a metal block as 250 g and the volume of water displaced as 50 cm^3. Calculate the density of the metal in kg/m^3.

Answer: Density = mass/volume = 250 g / 50 cm^3 = 5 g/cm^3 = 5000 kg/m^3

Question 2: If the measured density of a substance is significantly different from its known density, suggest two possible reasons for this discrepancy.

Answer: Measurement errors such as inaccurate weighing or volume reading; or impurities in the sample affecting its density.

Question 1: Describe how density measurements are important in the manufacturing of aircraft components made from aluminium.

Answer: Density measurements ensure the aluminium used is of the correct quality and weight; lighter components improve fuel efficiency and safety.

Question 2: Explain why understanding the density of materials is important in the construction and engineering industries.

Answer: It helps in selecting appropriate materials for structural stability, weight considerations, and ensuring safety and durability of constructions.

Question 1: A cube of metal measures 4 cm on each side and has a mass of 320 g. Calculate its density in kg/m^3. Then, explain how this measurement could be used to identify the metal type.

Answer: Volume = side^3 = 4 cm x 4 cm x 4 cm = 64 cm^3; Convert to m^3 = 64 x 10^-6 m^3; Density = mass/volume = 320 g / 64 cm^3 = 5 g/cm^3 = 5000 kg/m^3. Comparing this density to known densities of metals can help identify the metal, such as aluminium.