一颗彗星沿着一条非常细长的轨道运行，靠近太阳，然后向外飞去很远。对于定性模型来说，哪个表述最准确？

Question

BlackTom AI · Accepted Answer

Question restatement: A comet travels along a very elongated orbit, speeds up when near the Sun, and slows down as it moves far away. Which qualitative statement best describes this behavior in a simple model?

Option A: 'Because space is empty, the comet moves at the same speed everywhere.' This is incorrect because there is a central gravitational force from the Sun that changes the comet's speed as it moves along its orbit, so speed is not constant.

Option B: 'The comet speeds up near the Sun and, when far away, is slowed by the Sun’s gravitational pull.' This captures the key idea of orbital energy exchange: as the comet falls toward the Sun, gravitational potential energy converts to kinetic energy, increasing speed; as it climbs away, kinetic energy decreases and speed drops due to decreasing gravitational influence.

Option C: 'The speed changes randomly and is independent of position.' This is false because orbital mechanics impose a clear relation between speed and distance to the Sun through conserved energy and angular momentum; the motion is not random.

Option D: 'The comet only accelerates when it leaves the Sun.' This contradicts the physics of an elliptical orbit, where acceleration (change in velocity) is strongest when the comet is closest to the Sun (perihelion) and diminishes as it recedes; accelerating only during departure from the Sun ignores the entire inward part of the orbit.

Additional nuance: In a definitive qualitative model of a bound orbit around a central mass, the speed is not uniform, and the fastest point is near perihelion while the slowest point is near aphelion. The second option aligns with that concept, whereas the others misstate how gravity governs orbital motion.

In summary, option B correctly describes the velocity behavior as a function of distance to the Sun, while options A, C, and D misrepresent how central gravity shapes the comet’s speed along its elongated orbit.

国际科学 1A MS-ESS1-2：太阳系和银河系中的引力和运动 - 测验 2

一颗彗星沿着一条非常细长的轨道运行，靠近太阳，然后向外飞去很远。对于定性模型来说，哪个表述最准确？

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类似问题

If you drop something off the Empire State Building, why doesn't it orbit the Earth?

What causes an asteroid to drop out of orbit and travel toward Earth?

Which location is the Perihelion?

If the Sun disappeared, what would happen to the Earth’s orbit?

低地球轨道上的一颗卫星短暂启动推进器，以提高其沿路径的速度。从定性角度来看，它的轨道会发生什么变化？

Which of these observations would allow you to measure the mass of a planet?

The point in the Earth's orbit around the Sun where the Earth is closest to the Sun is known as the:

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国际科学 1A MS-ESS1-2：太阳系和银河系中的引力和运动 - 测验 2

一颗彗星沿着一条非常细长的轨道运行，靠近太阳，然后向外飞去很远。对于定性模型来说，哪个表述最准确？

查看解析

登录即可查看完整答案

类似问题

If you drop something off the Empire State Building, why doesn't it orbit the Earth?

​What causes an asteroid to drop out of orbit and travel toward Earth?

Which location is the Perihelion?

If the Sun disappeared, what would happen to the Earth’s orbit?

低地球轨道上的一颗卫星短暂启动推进器，以提高其沿路径的速度。从定性角度来看，它的轨道会发生什么变化？

Which of these observations would allow you to measure the mass of a planet?

The point in the Earth's orbit around the Sun where the Earth is closest to the Sun is known as the:

更多留学生实用工具

希望你的学习变得更简单

What causes an asteroid to drop out of orbit and travel toward Earth?