Planets move round the sun due to

Options

A. mutual attraction and repulsion between sun and planet
B. frictional force
C. centrifugal force
D. gravitational attraction between the sun and planets

Answer

To solve the question "Planets move round the sun due to," we will analyze the options provided and determine the correct reason for the planetary motion around the sun.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the reason why planets orbit the sun. This involves understanding the forces at play in the solar system.

2. **Analyzing the Options**:
- **Option 1: Mutual attraction and repulsion between sun and planet**: This option suggests that there is both attraction and repulsion. However, gravitational force is only an attractive force, so this option is incorrect.
- **Option 2: Frictional force**: Frictional force is not a factor in the motion of planets in space, as space is a vacuum. Therefore, this option is also incorrect.
- **Option 3: Centrifugal force**: Centrifugal force is a perceived force that acts outward on a mass moving in a circular path. It is not a real force that causes planets to orbit, so this option is incorrect.
- **Option 4: Gravitational attraction between the sun and planets**: This option states that the gravitational force is the reason for the planets' motion. The gravitational force is an attractive force that pulls the planets towards the sun, causing them to move in an orbit.

3. **Applying the Gravitational Force Formula**: The gravitational force \( F \) between two masses (the sun and a planet) is given by the formula:
\[ F = \frac{G \cdot M_s \cdot M_p}{r^2} \]
where:
- \( G \) is the gravitational constant,
- \( M_s \) is the mass of the sun,
- \( M_p \) is the mass of the planet,
- \( r \) is the distance between the centers of the two masses.

4. **Conclusion**: Since the gravitational force is the only force that acts between the sun and the planets, and it is an attractive force, it is the reason why planets move around the sun.

5. **Final Answer**: The correct answer is **Option 4: Gravitational attraction between the sun and planets**.