2016: Problem 8

Topic: Gravity
Concepts: Conservation of angular momentum, Kepler’s laws

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Solution:

Kepler’s laws:

• I) Derived from assuming force $F \propto 1/r^2$, potential energy $V \propto 1/r$
• II) Equivalent to conservation of angular momentum which holds for any central force such as $F \propto 1/r^3$
• III) Derived from assuming force $F \propto 1/r^2$, potential energy $V \propto 1/r$

Thus, the answer is B.

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