Unformatted text preview: Problem: Gravity is a central force. For any object subject to a central force, what can be said about the torque on the object about the force center (for example, does the sun exert a torque on the earth)? What about angular momentum? Solution A central force acts along the line connecting the centersofmass of the two objects. For a force to exert a torque on an object, there must be a component of the force which is perpendicular to the displacement vector between the objects; since the displacement from the sun to the earth, for example, is parallel to the force of the sun on the earth, the torque is zero (or v τ s,e = v r s.e × v F s,e = 0 , since v r b v F ). Any time net torque is zero, angular momentum is conserved. This will be the case for any object under the in±uence only of central forces (so angular momentum is a constant of motion for any orbit). Total Points for Problem: 1 Points...
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 Spring '08
 Stewart
 Physics, Force, Mass, Work, General Relativity, total points

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