Kinetic energy of plate tectonics problem

[hndalama]

Homework Statement

One effect of plate tectonics is that the North American continental plate moves across the Earth’s surface at a speed of about 1.15 cm/yr. The North American plate has an area of about 35 million square kilometers, an average thickness of about 25 km, and a density of about 3 g/cc. What is the kinetic energy associated with this movement?

Homework Equations

0.5mv²

The Attempt at a Solution

volume=area*thickness
volume= 35 *10⁹ * 25000 = 8.75 *10¹⁴ m³
density =3 g/cc = 3000 kg/m³
velocity= 1.15cm/yr = 3.697*10^-10 m/s

mass = density * volume
mass= 8.75 *10¹⁴ m³ * 3000 kg/m³
mass = 2.625 * 10¹⁸ kg

kinetic energy = 0.5mv²
0.5 * 2.625 * 10¹⁸ * (3.697*10^-10)²
= 0.179 Joules
My answer is marked wrong but what's wrong with it?

 

[gneill]

Check your conversion from square kilometers to square meters for the area.

 

[PetSounds]

Check your unit conversions.

EDIT: Beat me to it.

 

[hndalama]

oh I see my mistake now, thanks for your help