A body is in the state of rest on the surface of earth. Which of the following is a correct statement?

Options

A. Frictional force acts on the body
B. Only the weight of body acts on it
C. Only the reaction of the earth acts on it
D. The weight of body acting downward is equal and opposite to the reaction of the earth.

Explanation

To solve the question, "A body is in the state of rest on the surface of the earth. Which of the following is a correct statement?", we will analyze the forces acting on the body.

### Step-by-Step Solution:

1. **Identify the Forces Acting on the Body**:
- When a body is at rest on the surface of the Earth, two main forces act on it:
- The weight of the body (mg) acting downwards due to gravity.
- The normal force (reaction force) exerted by the Earth acting upwards.

2. **Understanding Weight and Normal Force**:
- The weight of the body is given by the formula:
\[ \text{Weight} = m \cdot g \]
where \( m \) is the mass of the body and \( g \) is the acceleration due to gravity.
- According to Newton's third law of motion, for every action, there is an equal and opposite reaction. Therefore, the normal force exerted by the Earth on the body is equal in magnitude and opposite in direction to the weight of the body.

3. **Analyzing the State of Rest**:
- Since the body is at rest, it means that the net force acting on it is zero. This can be expressed mathematically as:
\[ \text{Net Force} = \text{Weight} - \text{Normal Force} = 0 \]
- This implies:
\[ \text{Weight} = \text{Normal Force} \]

4. **Evaluating the Options**:
- Now, let's evaluate the provided statements:
1. **Frictional force acts on the body**: This is incorrect because the body is at rest and there is no relative motion, hence no friction.
2. **Only the weight of the body acts on it**: This is incorrect because the normal force also acts on the body.
3. **Only the reaction of the earth acts on it**: This is incorrect because the weight of the body also acts on it.
4. **The weight of the body acting downward is equal and opposite to the reaction of the earth**: This is correct, as per our analysis.

5. **Conclusion**:
- The correct statement is option 4: "The weight of the body acting downward is equal and opposite to the reaction of the Earth."