# Homework Help: Gravitational fields

1. Oct 2, 2011

### xxabr

1. The problem statement, all variables and given/known data
It can be assumed that the Earth, to a good approximation, moves in a circular orbit about the sun. Determine the speed of the Earth.

2. Relevant equations
v2 = GMearth/r

3. The attempt at a solution
mearth= 5.98x1024
R of earths orbit= 1.49x1011
G= 6.67x10-11

v2= (6.67x10-11)(5.98x1024)/ (1.49x1011)
v2= (3.98x1014) / (1.49x1011)
v= $\sqrt{}2676.9$
v= 51.7m/s

Now here's the problem. My teacher said that the answer to this question is 2.97x104m/s
What is it that I am doing wrong? D:

2. Oct 2, 2011

### Staff: Mentor

The important mass, the one that the Earth orbits, is the mass of the Sun.

3. Oct 2, 2011

### xxabr

Ohhhh. Okay, I got it. Thank you