# Homework Help: Radiation and temperature time

1. Jul 18, 2009

### intenzxboi

1. The problem statement, all variables and given/known data

The Earth intercepts 1.27 ´ 1017 W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 ´ 1021 m3, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

no clue how to start.
what formulas are related to this problem

2. Jul 18, 2009

### Redbelly98

Staff Emeritus
What formulas has your class studied recently? I would look at those.

3. May 17, 2010

### Yanbeast

I'm not entirely sure either. But using Q=cmT to find out the energy needed to heat the water, and then dividing by the intercepted energy.

Q=4x(1.08x10^26)x100

=4.32x10^26

Then divide by the intercepted power. Which converts to J/s.

The answer comes out wrong though.

4. May 17, 2010

### Redbelly98

Staff Emeritus
You used the wrong value of c. Hint: pay attention to units.