Final answer:
The radius and diameter of a circle with a diameter of 18 cm are 9 cm and 18 cm, respectively. The density of a material filling a 2 cm sided cube is 3 g/cm³, and for a brick shaped material with dimensions of 2 cm × 4 cm × 8 cm, the density is 2 g/cm³.
Step-by-step explanation:
The radius of a circle with a diameter of 18 cm is 9 cm because the radius is half of the diameter. Therefore, the radius is 9 cm, and the diameter is 18 cm.
To calculate the density of a material, you can use the formula density = mass/volume. For a cube measuring 2 cm on each side, the volume is 2 cm × 2 cm × 2 cm = 8 cm³. Consequently, if 24 g of material fills this cube, the density is 24 g / 8 cm³ = 3 g/cm³.
Similarly, for a brick shaped material with dimensions 2 cm wide, 4 cm high, and 8 cm long, the volume is 2 cm × 4 cm × 8 cm = 64 cm³. Therefore, if 128 g of material occupies this volume, the density is 128 g / 64 cm³ = 2 g/cm³.