# Work done on the Earth by the Sun

1. Dec 12, 2007

### nothing123

Hi,

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

I was just wondering, because the earth follows an elliptical path around the sun and the gravitational force of the sun on the earth is towards the sun, would the work done on the earth be considered positive or negative?

2. Relevant equations

3. The attempt at a solution

Thanks.

2. Dec 12, 2007

### Shooting Star

Because of the ellipticity, the speed of the earth varies. When the KE of the earth increases, work done on earth is positive and vice versa. During a complete orbit however, the total work done is zero.

3. Dec 12, 2007