physics : class11 Elliptical Orbit : Second Law of Kepler : Gravitation MCQ Questions and Answers
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Elliptical Orbit
MCQ questions and answers.
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MCQ Questions
1. What is the shape of the orbit of a planet around the Sun according to Kepler's first law?
A.
Circular
B.
Elliptical
C.
Parabolic
D.
Straight-line
Correct Answer:
Elliptical
Explanation:
According to Kepler's first law, each planet moves around the Sun in an elliptical orbit, with the Sun at one focus of the ellipse.
2. In a planet's elliptical orbit, where is the Sun located?
A.
At the centre of the ellipse
B.
At one focus of the ellipse
C.
At both foci of the ellipse
D.
Outside the ellipse
Correct Answer:
At one focus of the ellipse
Explanation:
The Sun is located at one focus of the elliptical orbit, not at its centre.
3. The point in an elliptical orbit where a planet is nearest to the Sun is called:
A.
Aphelion
B.
Perihelion
C.
Equinox
D.
Zenith
Correct Answer:
Perihelion
Explanation:
Perihelion is the point on an elliptical orbit at which the planet is closest to the Sun.
4. The point in an elliptical orbit where a planet is farthest from the Sun is called:
A.
Perihelion
B.
Aphelion
C.
Focus
D.
Eccentricity
Correct Answer:
Aphelion
Explanation:
Aphelion is the point on an elliptical orbit at which the planet is farthest from the Sun.
5. According to Kepler's second law, the line joining the Sun and a planet sweeps out:
A.
Equal distances in equal times
B.
Equal areas in equal times
C.
Equal angles in equal times
D.
Equal speeds in equal times
Correct Answer:
Equal areas in equal times
Explanation:
Kepler's second law states that the radius vector from the Sun to the planet sweeps out equal areas during equal intervals of time.
6. When a planet moves closer to the Sun in its elliptical orbit, its speed generally:
A.
Increases
B.
Decreases
C.
Becomes zero
D.
Remains exactly constant
Correct Answer:
Increases
Explanation:
To sweep equal areas in equal times, a planet moves faster when it is nearer the Sun, especially near perihelion.
7. When a planet is near aphelion in its elliptical orbit, its speed is generally:
A.
Maximum
B.
Minimum
C.
Infinite
D.
Equal to zero
Correct Answer:
Minimum
Explanation:
A planet moves most slowly near aphelion, the point farthest from the Sun, while still satisfying the equal-area law.
8. For equal time intervals, the areas swept out by the line joining the Sun to a planet are:
A.
Larger near perihelion
B.
Larger near aphelion
C.
Equal
D.
Always zero
Correct Answer:
Equal
Explanation:
Kepler's second law requires equal areas to be swept out in equal time intervals, even though the planet's speed changes along the elliptical orbit.
9. A planet travels from point P to point Q in an elliptical orbit during a fixed time interval. The area swept by the Sun-planet line depends primarily on:
A.
The area law of Kepler
B.
The colour of the planet
C.
The size of the planet
D.
The number of moons
Correct Answer:
The area law of Kepler
Explanation:
Kepler's second law determines the swept area: equal time intervals correspond to equal swept areas in the elliptical orbit.
10. Why does a planet move faster near perihelion than near aphelion in an elliptical orbit?
A.
To sweep equal areas in equal times
B.
Because the orbit becomes circular there
C.
Because the Sun stops attracting it
D.
Because the planet becomes larger there
Correct Answer:
To sweep equal areas in equal times
Explanation:
Near perihelion, the planet is closer to the Sun, so it must move faster to sweep the same area in the same time as it does near aphelion.
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