#### Kepler's Law: The Mathematical Formula for Planetary Motion

In 1609, Johannes Kepler published his first two laws of planetary motion, which laid the mathematical foundation for our understanding of how planets move in space. Kepler's First Law states that planets move in elliptical orbits with the sun at one focus. Kepler's Second Law states that a planet's orbital speed is directly proportional to its distance from the sun. These laws are still used today to calculate the paths of spacecraft and predict eclipses. In this post, we will explore Kepler's Laws in more detail and see how they can be applied to real-world situations!

#### Kepler's First Law: The orbit of a planet is an ellipse with the sun at one of the foci.

An ellipse is a closed curve where the sum of the distances from any point on the curve to both foci is constant. This means that, as a planet moves around its orbit, it will sometimes be closer to the sun (perihelion) and sometimes be further away (aphelion). Kepler's First Law can be used to calculate the size of a planet's orbit. For example, if we know the distance from the sun to the planet at perihelion and aphelion, we can use Kepler's First Law to calculate the size of the orbit!

#### Kepler's Second Law: A planet's orbital speed is directly proportional to its distance from the sun.

This law states that a planet moves faster when it is closer to the sun and slower when it is further away. Kepler's Second Law can be used to calculate a planet's orbital period (the time it takes to complete one orbit). For example, if we know the distance from the sun to a planet at perihelion and aphelion, we can use Kepler's Second Law to calculate the orbital period!

Following are some of the multiple choice questions on the **Kepler's Law** with answers that will help the students in developing their knowledge.

## Kepler's Law MCQ

### 2. A year on Jupiter is 4,344 days long. This tells you how long it takes

### 4. The period of geostationary artificial satellite is

### 5. Earth's spinning on its axis is called its _____________.

### 7. Kepler’s third law states

### 8. When the earth is closest to the sun

### 10. When a planet orbits the Sun, one of the foci of the elliptical orbit is

### 11. Planets revolve around the sun in elliptical orbits

### 12. How fast does the earth revolve around the sun?

### 13. What is Kepler's 3rd Law?

### 14. What is his nationality

### 15. Which planet has the least eccentric orbit?

### 16. What is Kepler's 2nd Law?

### 17. What is Kepler's 1st Law?

### 18. What causes Earth’s year to be shorter than Jupiter’s year?

### 19. Double the product of the masses of two objects

### 20. What unit to we usually use to to measure a planet's orbital period?

### 21. What will result in the most eccentric elliptical orbit

### 22. What is it called when earth reaches the point in orbit when it is farthest from the sun?

### 23. Which model of the solar system can explain all observations

### 24. What is the name of the backward motion of planets that cannot be explained by the geocentric model?

### 27. When the distance between two objects increases the gravitational force between them

### 28. When the mass of the objects increases the gravitational force between them

### 29. Who proposed Earth centered model?

### 30. Types of celestial coordinate system

### 31. What family is he from?

### 32. What is the second law of Kepler ?

### 33. What is the third law of Kepler

### 34. What is the line connecting the sun and planet

### 36. The accelerations due to gravity on the surfaces of two planets are equal in magnitudes if

### 37. If r represents the radius of the orbit of a satellite of mass m moving round a planet of mass M the velocity of the satellite is given by

### 38. What is the reason for the motion of the moon on its orbit?

### 39. What is the correct formula to calculate eccentricity?

### 40. The factors that can determine the force between two objects include all of the following except

### 41. Where are the focal points located in a perfect circle?

### 42. Earth will travel fastest in its orbit when

### 43. Which statement correctly describes when the earth is closest to the sun

### 44. The planet with the most eccentric orbit is

### 45. What effect does increasing the distance between an ellipse’s foci have on the shape of an ellipse?

### 46. How can the position of the sun in earth's orbit be described?

### 47. Where will an object move at the greatest speed as it orbits the sun?

### 48. What did Kepler discover about planets and their orbital speed?

### 49. Double the distance between two objects

### 50. Which of the following can decrease the gravity between objects?

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