# Question: 2 how much mass in kilograms radioactive material is need...

###### Question details

2. How much mass (in kilograms) radioactive material is need to power Earth’s interior over its lifetime? What fraction of Earth's mass is this?

The flow of heat from Earth's interior to the surface is estimated to be 50 terawatt (1 terawatt = 1 e12 joule/sec) and comes from two main sources in roughly equal amounts: th energy produced by the radioactive decay of isotopes, and the energy left over from the formation of the Earth.

All numbers must be entered as 5000 or 5e3 or 5.0e3 and
**not** with commas as in "5,000" and
**not**as fractions as in "3/4" and
**not** as percentages as in "70%".

Estimate the age of Earth (in year).

Using the hint provided, estimate the energy (in joule) produced from radioactivity over the Earth's lifetime.

Estimate the energy density (in joule/kg) of nuclear fission fuels.

Estimate mass (in kg) of radioactive material is need to power Earth’s interior over its lifetime.

Estimate the mass of Earth (in kg).

Estimate the fraction of Earth's mass in radioactive material.