Which of the following are Kepler's laws ?

Options

A. Law of orbits
B. Law of continutiy
C. Law of areas
D. Law of periods

Answer

To determine which of the given options are Kepler's laws, we will analyze each statement based on our knowledge of Kepler's laws of planetary motion.

### Step-by-Step Solution:

1. **Identify Kepler's Laws**:
- Kepler formulated three laws of planetary motion:
- **First Law (Law of Orbits)**: This law states that the planets move in elliptical orbits with the Sun at one of the foci.
- **Second Law (Law of Areas)**: This law states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time, meaning that the areal velocity is constant.
- **Third Law (Law of Periods)**: This law states that the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit (the average distance from the Sun).

2. **Evaluate the Given Options**:
- **Law of Orbits**: This corresponds to Kepler's First Law.
- **Law of Continuity**: This is not one of Kepler's laws.
- **Law of Areas**: This corresponds to Kepler's Second Law.
- **Law of Periods**: This corresponds to Kepler's Third Law.

3. **Conclusion**:
- The correct Kepler's laws from the options provided are:
- Law of Orbits (1st Law)
- Law of Areas (2nd Law)
- Law of Periods (3rd Law)
- Therefore, the correct answers are 1, 3, and 4.

### Final Answer:
The Kepler's laws among the options given are:
- Law of Orbits (1)
- Law of Areas (3)
- Law of Periods (4)