The Earth has a rotational period of 23 hours, 56 minutes. The moon has a rotational period of 27.3 days and an orbital period of 27.3 days. The moon has a radius of 1.74 x10^6 m, an orbital radius of 3.82 x10^8 m, and a mass of 7.36 x10^22 kg. The earth has a radius of 6.37 x10^6 m and a mass of 5.98 x10^24 kg. Assume that the moon has a circular orbit around the earth and that the three angular angular momentum vectors are parallel (which isn't really the case).(adsbygoogle = window.adsbygoogle || []).push({});

a) calculate the angular momentum of the Earth-moon system. All of the rotations are counterclockwise.

i used the relation T=2pi/omega to solve for omega for both earth and the moon. assuming both the earth and the moon are solid spheres, I=.4MR^2. then i used L=I times omega to get L for both the earth and the moon. and then adding earth and moon's L's gives me the L for the system. right?

b) If, due to torques internal to the Earth-mmon system, the earth's day is being lengthened by the rate of 1.48 ms/century, calculate the average torque exerted on the Earth by the moon.

since T is increasing, Earth's angular velocity has to be decreasing. but how do i go about finding the torque? rFsin theta? dL/dt ?

i'm hoping someone can help me get a good start. thanks.

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# Homework Help: Rotation: the earth-moon system

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