Final answer:
The mass of a solid iron ball with a radius of 18cm is approximately 193 kg.
Step-by-step explanation:
The mass of a solid iron ball can be calculated using its volume and density. The formula for the volume of a sphere is V = (4/3)πR³, where R is the radius of the sphere. Given the radius of 18cm, the volume of the iron ball is:
V = (4/3)π(18cm)³ = 24408cm³
The density of iron is 7.9 g/cm³. Using the formula density = mass/volume, we can rearrange the formula to solve for mass:
mass = density x volume = 7.9 g/cm³ x 24408cm³ = 192763.2 g
Rounded to two significant figures, the mass of the iron ball is approximately 193 kg.