Calculating Earth's Speed Around the Sun

[1irishman]

Homework Statement

The Earth travels around the sun in a circle of radius 150 million km and does a complete cycle in about 365 days. Find its speed.

Homework Equations

v= d/t

The Attempt at a Solution

d = 1000m/1km x 150,000,000km = 1.5 x 10^11m
There are 31,536,000 seconds in 1year.
v = 1.5 x 10^11/31,536,000 = 4.7 x 10^18 they say this is wrong answer and the right answer is actually 29 800 m/s.
Please help? Thank you.

 

[physicsface]

Find the circumference of Earth's orbit. You used the radius.

 

[tnutty]

d = circumfrence = 2piR= 2 * 3.1415 * 150 * 10^6km
t = 365 day.
s = d(in meters) / t(in seconds)

 

[1irishman]

it's been solved...i calculated circumferance and it worked out to be the right answer. thank you!