1. The problem statement, all variables and given/known data A)Calculate the magnitude of the angular momentum of the earth in a circular orbit around the sun. B) Is it reasonable to model it as a particle? Yes, considering the size of the Earth in comparison of its orbit around the sun it is reasonable to model it is a particle. 2. Relevant equations L = I*ω (when considering the Earth as a rigid body) L=r*p I=mE*rE 3. The attempt at a solution Assuming the Earth has a completely circular orbit: The Earth's orbit is 2∏ radians, it completes this orbit in one year. 1 year = 3.145*107 s 2∏/3.156*107 = 1.99*10-7rad/s Average linear speed = ω*r (radius of orbit which is 1AU or 1.49*1011 (1.99*107)*(1.49*1011)=2.977*1018m/s So, using the formula L=r x p (1.49*1011)*(2.977*1018)*sin90°=4.45*1029m^2/s But, this was not the answer masteringphysics was looking for. So, using the formula L=Iω I calculated I (mass of the Earth*radius) = (3.81*1031)*(1.99*10-7) = 7.58*1024 kg*m2/s And that's also not the answer masteringphysics was looking for. I'm not sure if I made a mistake somewhere in my calculations or if I'm not using the right values for mass, radius of Earth etc. Because Earth's orbit is non circular I'm not sure at what point in Earth's orbit they wanted us to consider as the radius. I choose one AU because it's an averaged value. Thoughts?