Significance of a planet's "surface gravity"

In summary, the surface gravity of Uranus is only 90% of Earth's due to its lower density, which increases the distance between its surface and core. However, this does not affect its overall gravitational force towards other objects. At equal distances, Uranus would have a greater pull on an object compared to Earth.
  • #1
lifeonmercury
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I was just looking at list of solar system objects and was surprised to see that the surface gravity of Uranus is only 90% that of Earth's. I get it that the "surface" of a gas planet is further from that planet's core than is the case for Earth.
But does surface gravity really have any effect on a planet's overall gravitational force toward other objects? For example, would Uranus still have a considerably greater tug on an asteroid passing 100,000 miles away from it than the Earth would have on an asteroid passing by Earth at the same distance?
 
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  • #2
lifeonmercury said:
I was just looking at list of solar system objects and was surprised to see that the surface gravity of Uranus is only 90% that of Earth's. I get it that the "surface" of a gas planet is further from that planet's core than is the case for Earth.
But does surface gravity really have any effect on the planet's overall gravitational force toward other objects? For example, would Uranus still have a considerably greater tug on an asteroid passing 100,000 miles away from it than the Earth would have on such an asteroid passing by Earth at the same distance?
At equal distances, Uranus would have a greater pull on the object. The reason that Uranus has a lesser surface gravity is because it is much less dense than the Earth (about 24% that of the Earth's). This increases the distance the surface has from the center even more than what it would have been if the densities had been equal.
 

FAQ: Significance of a planet's "surface gravity"

1. What is the significance of a planet's surface gravity?

A planet's surface gravity is a measure of the strength of the gravitational force at its surface. This force is what keeps objects, such as people and buildings, from floating off into space. It also plays a crucial role in determining a planet's atmosphere, climate, and ability to sustain life.

2. How is a planet's surface gravity calculated?

A planet's surface gravity is calculated using the formula g = GM/r^2, where g is the surface gravity, G is the universal gravitational constant, M is the mass of the planet, and r is the radius of the planet. This formula takes into account both the mass and size of the planet to determine its surface gravity.

3. How does a planet's surface gravity affect the weight of objects?

As the surface gravity of a planet increases, the weight of objects on its surface also increases. This is because the gravitational force pulling them towards the planet's center is stronger. For example, a person who weighs 100 pounds on Earth would weigh approximately 38 pounds on Mars, where the surface gravity is about one-third that of Earth's.

4. Can a planet's surface gravity change over time?

Yes, a planet's surface gravity can change over time due to various factors such as geological processes, changes in the planet's mass, or interactions with other objects in space. However, these changes are usually very small and happen over long periods of time.

5. How does a planet's surface gravity affect its ability to retain an atmosphere?

A planet's surface gravity plays a crucial role in determining its ability to retain an atmosphere. If a planet has a weak surface gravity, it may not be able to hold onto its atmosphere, and gases may escape into space. On the other hand, a planet with a strong surface gravity, like Earth, can retain its atmosphere and support life.

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