Question

A plastic beach ball has radius 21.6 cm and mass 0.100 kg, not including the air inside. Assume the air density is 1.30 kg/m3 both inside and outside. What is the weight of the beach ball including the air inside?

Answer 1

Answer: 0.1416 kg

Explanation:

Total Mass = Mass of beach ball + Mass of air inside

Mass of beach ball = 0.100 kg

Mass of air = density * volume

Density = 1.30 kg/m^3

Radius (r) = 21.6 cm = 0.216 m

Volume (sphere) = π * r^3 = π * (0.216)^3 = 0.032 m^3

Hence:

Mass of air = 1.30 * 0.032 = 0.0416 kg

Total Mass = 0.100 + 0.0416 = 0.1416 kg

Answer 2

Answer: 0.1416 kg

Explanation:

Total Mass = Mass of beach ball + Mass of air inside

Mass of beach ball = 0.100 kg

Mass of air = density * volume

Density = 1.30 kg/m^3

Radius (r) = 21.6 cm = 0.216 m

Volume (sphere) = π * r^3 = π * (0.216)^3 = 0.032 m^3

Hence:

Mass of air = 1.30 * 0.032 = 0.0416 kg

Total Mass = 0.100 + 0.0416 = 0.1416 kg