Help with Astronomy 101 Questions: Orbit Radius & Angular Diameter

  • Thread starter msyvette
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In summary, the conversation is about someone asking for help with two questions. The first question involves calculating the circular velocity of a satellite orbiting the Earth with a given mass and orbit radius. The second question asks for the angular diameter of an object given its distance and linear diameter. The speaker suggests using formulas and drawing a picture to solve the second question, but cannot provide further assistance due to forum rules.
  • #1
msyvette
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I need help please. i have a couple of questions if someone could please help me with.

1. If a satellite with a small mass (any #) is orbiting the Earth with an orbit radius of 4000000m, what is the circular velocity of the satellite?

2. if the distance to an object is 4000000 km and the linear diameter if the same object is 2250 km, what is the angular diameter of the object in degrees?
 
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  • #2
What formulas do you think might apply here? Have you drawn a picture for the second one?

Sorry I can't be more helpful... forum rules that we won't do homework for you.

Post what you've tried - we'll be more than happy to help you a bit more.
 
  • #3


Sure, I'd be happy to help with your questions about orbit radius and angular diameter in Astronomy 101. Here are the answers to your two questions:

1. The circular velocity of a satellite in orbit is determined by the formula v = √(GM/r), where G is the gravitational constant (6.67 x 10^-11 Nm^2/kg^2), M is the mass of the central body (in this case, the Earth), and r is the orbit radius. Plugging in the values given, we get v = √((6.67 x 10^-11 Nm^2/kg^2)(5.97 x 10^24 kg)/4000000m) = 7673 m/s. So the circular velocity of the satellite is approximately 7673 m/s.

2. The angular diameter of an object can be calculated using the formula θ = 2arctan(d/2D), where d is the linear diameter of the object and D is the distance to the object. Plugging in the values given, we get θ = 2arctan((2250 km/2)/(4000000 km)) = 0.032 degrees. So the angular diameter of the object is approximately 0.032 degrees.

I hope this helps! If you have any further questions, please feel free to ask. Good luck with your studies in Astronomy 101!
 

Related to Help with Astronomy 101 Questions: Orbit Radius & Angular Diameter

1. What is the difference between orbit radius and angular diameter?

Orbit radius refers to the distance between an object and the point it is orbiting around, while angular diameter is the apparent size of an object as viewed from a specific point. In astronomy, orbit radius is measured in units such as kilometers or astronomical units (AU), while angular diameter is measured in degrees or arcminutes.

2. How do you calculate the orbit radius of a planet?

To calculate the orbit radius of a planet, you can use Kepler's Third Law of Planetary Motion, which states that the square of the orbital period is directly proportional to the cube of the semi-major axis (half of the longest axis) of the orbit. This can be expressed as R3 = T2, where R is the orbit radius and T is the orbital period. By rearranging the equation, you can calculate the orbit radius using the known orbital period of the planet.

3. How does the orbit radius affect the speed of a planet?

The orbit radius and speed of a planet are inversely related. This means that the farther a planet is from the object it is orbiting, the slower its speed will be. This relationship is described by Kepler's Second Law of Planetary Motion, which states that a planet will sweep out equal areas in equal times, meaning that the speed of a planet will decrease as it moves farther from the object it is orbiting.

4. How is angular diameter measured in astronomy?

Angular diameter is typically measured using an instrument called a micrometer, which can measure the angle subtended by an object at a specific distance. In astronomy, angular diameter is often measured in degrees, arcminutes, and arcseconds. One degree is divided into 60 arcminutes, and one arcminute is divided into 60 arcseconds.

5. Can the orbit radius and angular diameter of an object change?

Yes, the orbit radius and angular diameter of an object can change over time. For example, the orbit radius of a planet may change due to gravitational interactions with other objects, and the angular diameter of a star may change as it goes through different stages of its life cycle. Additionally, the apparent angular diameter of an object can change depending on the observer's position and the atmospheric conditions.

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