# Question :S

## Homework Statement

By how much does the mass of the earth increase each year as a result of sunlight reaching it? Radiation from the sun reaches the EArth at a rate of 1400W/m^2 of area perpendicular to the energy flow. Assume 100% absorption.

## Homework Equations

I'm sorry but I havent the slightest clue as to how to approach this question.
But we are given the Radius of the Earth as 6.36 * 10 ^6 m

## The Attempt at a Solution

The answer is sopposed to be 1.23 * 10^8

## Answers and Replies

malawi_glenn
Science Advisor
Homework Helper
I'll give you a hint: What is the area that is seen by the rays coming from the sun?

First to answer your question: only half the surface area? Which would be 2pi r^2

So we have to solve for power useing power = rate * surface area

then solve for energy useing energy = power * time

then E = mc^2 to solve for mass..

Would this mass be the increase or the mass after one year?

Dick
Science Advisor
Homework Helper
Cross sectional area. Not 1/2 of surface area. Cross section, i.e. pi*r^2. And yes, you seem to know how to calculate the rate of energy absorption and solve for the equivalent mass.