Cuesta College, San Luis Obispo, CA
According to Kepler's __________, a planet in an elliptical orbit will move most rapidly when it is closer the sun.
(A) first law (orbits of the planets are ellipses with the sun at one focus).
(B) second law (a line from a planet to the sun sweeps over equal areas in equal intervals in time).
(C) third law (a planet's orbital period squared is proportional to its average distance from the sun cubed).
(D) (Kepler's laws do not vary the speed of a planet along its orbit.)
Correct answer: (B)
Kepler's second law is a statement of the conservation of angular momentum, where a planet will move fastest when closest to the sun in an elliptical orbit, and move slowest when farthest from the sun. This is analogous to the rotation of an ice skater, where the rate of rotation will increase as arms and legs are brought in closer to the body, and the rate of rotation will decrease as arms and legs are outstretched.
(A) first law (orbits of the planets are ellipses with the sun at one focus).
(B) second law (a line from a planet to the sun sweeps over equal areas in equal intervals in time).
(C) third law (a planet's orbital period squared is proportional to its average distance from the sun cubed).
(D) (Kepler's laws do not vary the speed of a planet along its orbit.)
Correct answer: (B)
Kepler's second law is a statement of the conservation of angular momentum, where a planet will move fastest when closest to the sun in an elliptical orbit, and move slowest when farthest from the sun. This is analogous to the rotation of an ice skater, where the rate of rotation will increase as arms and legs are brought in closer to the body, and the rate of rotation will decrease as arms and legs are outstretched.
Section 70158
Exam code: quiz02k3P7
(A) : 7 students
(B) : 15 students
(C) : 10 students
(D) : 3 students
Success level: 46% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.20
Section 70160
Exam code: quiz02n3Ap
(A) : 6 students
(B) : 15 students
(C) : 8 students
(D) : 2 students
Success level: 53% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.49
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