mat-sln-asn-hwk24-spr02

mat-sln-asn-hwk24-spr02 - Problem: Gravity is a central...

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Solution for Homework 24 Gravitation I Solution to Homework Problem 24.1() Problem: What property does gravitational mass measure? What other physical characteristic coincides with gravitational mass? Solution The gravitational mass of an object is, apparently coincidentally, the same thing as an object’s inertia. So the property that causes an object to be gravitationally attracted to other objects is precisely the same property that causes the object to resist acceleration (a remarkable fact, which in part led Einstein to formulate General Relativity). Total Points for Problem: 1 Points Solution to Homework Problem 24.2() Problem: When is an object said to be “weightless”? Solution An object is said to be weightless when is is under no force other than that of gravity. In other words, an object is weightless when it is in freefall (for example, a satellite in orbit). Total Points for Problem: 1 Points Solution to Homework Problem 24.3()
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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 centers-of-mass 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 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 inuence 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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This note was uploaded on 05/04/2008 for the course PHYS 2054 taught by Professor Stewart during the Spring '08 term at Arkansas.

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