Weight dependent on planet size and rotation speed?

In summary, the conversation discusses the concept of weight on a larger planet with a faster rotation rate and how it could potentially affect a person's weight. The equation for the rotation's effect is also mentioned.
  • #1
NHsolarguy
1
0
Hi,
I recently read a sci-fi story where they implied that the planet was much larger than Earth, but because that planet was rotating much faster than Earth, a person's weight on this planet was similar to what it was on Earth. I always thought it was strictly the masses that controlled this... However, intuitively, if a body was rotating fast enough, I would think it would tend to fling away objects from the surface... So it certainly seems possible that rotation could affect weight. Does anyone have an equation handy for this?
thanks!
 
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  • #3


Hello, thank you for sharing your thoughts and question. The concept of weight being affected by planet size and rotation speed is definitely an interesting one. In terms of physics, weight is determined by the gravitational force exerted on an object by a planet. This force is directly proportional to the mass of the planet and inversely proportional to the square of the distance between the object and the planet's center of mass. So, in theory, a larger planet would have a stronger gravitational force and therefore a person would weigh more on that planet compared to Earth.

However, as you mentioned, the rotation speed of a planet can also play a role in weight. This is because the faster a planet rotates, the greater the centrifugal force it exerts on objects on its surface. This force is directed away from the planet's center and can counteract some of the gravitational force, making objects feel lighter. This is why people on a fast-spinning planet may feel lighter than they would on a slower-spinning one, even if the planets have the same mass.

Unfortunately, there is no single equation that can accurately calculate weight based on both planet size and rotation speed. This is because other factors such as the planet's density, shape, and distance from its star also play a role. However, scientists have developed models that take these factors into account and can estimate the weight of a person on different planets. These models use the planet's mass, radius, and rotation period to calculate the surface gravity, which is directly related to weight.

I hope this helps to clarify the relationship between weight, planet size, and rotation speed. It's always fascinating to explore the science behind science fiction concepts. Thank you for sparking this discussion!
 

1. How does the size of a planet affect its weight?

The size of a planet directly affects its weight through the force of gravity. The larger the planet, the greater its mass, and therefore the stronger the gravitational pull. This means that an object on a larger planet would weigh more compared to the same object on a smaller planet.

2. Does the rotation speed of a planet affect its weight?

Yes, the rotation speed of a planet also affects its weight. This is because the faster a planet rotates, the stronger the centrifugal force it exerts. This force acts in the opposite direction of gravity and can slightly decrease the weight of objects on the surface of a fast-spinning planet.

3. Are there other factors besides planet size and rotation speed that affect weight?

Yes, there are other factors that can affect weight, such as altitude and atmospheric pressure. On a planet with a denser atmosphere, objects would experience more resistance and therefore weigh slightly more compared to a planet with a thinner atmosphere. Additionally, altitude can also affect weight due to the decrease in gravitational pull at higher elevations.

4. How is weight on other planets measured and compared to Earth?

Weight on other planets is measured using a scale that takes into account the planet's size, rotation speed, and gravitational pull. This measurement is then compared to the weight of the same object on Earth, which is considered the standard for weight measurement.

5. Can the weight of an object change on a planet with different size and rotation speed?

Yes, the weight of an object can change on a planet with different size and rotation speed. As mentioned before, the force of gravity is affected by both the size and rotation speed of a planet, so an object's weight would vary depending on these factors. However, the object's mass would remain the same regardless of the planet it is on.

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