The following table shows the distance from the sun of some unknown planets of equal mass.
Distance from Sun
| Planet | Distance from Sun |
| :----- | :---------------- |
| W | 1.5 AU |
| X | 0.723 AU |
Which of the following best explains which planet revolves at a faster speed?
A. Planet X, because the gravitational force is strengthened by distance
B. Planet W, because the sun pulls it with a greater force
C. Planet W, because the gravitational force is weakened by distance
D. Planet X, because the sun pulls it with a less force
Answer (2)
Planet X is closer to the sun (0.723 AU) than Planet W (1.5 AU).
A smaller distance from the sun results in a stronger gravitational force.
A stronger gravitational force causes the planet to revolve faster.
Therefore, Planet X revolves faster because the gravitational force is strengthened by distance. Pl an e tX , b ec a u se t h e g r a v i t a t i o na l f orce i ss t re n g t h e n e d b y d i s t an ce
Explanation
Understanding the Problem We are given the distances of two planets, W and X, from the sun. We need to determine which planet revolves faster and why.
Key Concept The planet closer to the sun experiences a stronger gravitational force and, therefore, revolves faster.
Comparing Distances Planet W is 1.5 AU from the sun, and Planet X is 0.723 AU from the sun.
Determining the Closer Planet Since 0.723 AU < 1.5 AU, Planet X is closer to the sun than Planet W.
Conclusion Therefore, Planet X revolves faster because it experiences a stronger gravitational force from the sun. The gravitational force is strengthened by a smaller distance.
Examples
Imagine planets orbiting a star. The closer a planet is to the star, the stronger the star's gravitational pull on it. This stronger pull causes the planet to move faster in its orbit. This principle is similar to how satellites orbit the Earth; satellites closer to Earth orbit faster.
Planet X revolves faster than Planet W because it is closer to the sun, resulting in a stronger gravitational force acting on it. This stronger gravitational force enables faster orbital speeds. Therefore, the correct choice is that Planet X has a faster revolution due to being closer to the sun.
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