Homework Help: Kinetic energy of plate tectonics problem

1. Mar 4, 2017

hndalama

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

2. Relevant equations
0.5mv2

3. 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?

2. Mar 4, 2017

Staff: Mentor

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

3. Mar 4, 2017