A : The relative acceleration of two objects moving under the effect of gravity, only is always zero, irrespective of direction of motion.
R : The acceleration of object moving under the effect of gravity have acceleration always in downward direction and is independent from size and mass of object.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statement, then mark (4).

Answer

To solve the question, we need to analyze the assertion (A) and the reason (R) provided:

**Assertion (A):** The relative acceleration of two objects moving under the effect of gravity is always zero, irrespective of the direction of motion.

**Reason (R):** The acceleration of objects moving under the effect of gravity is always in the downward direction and is independent of the size and mass of the object.

### Step-by-Step Solution:

1. **Understanding Relative Acceleration:**
- Relative acceleration between two objects is defined as the acceleration of one object with respect to the other. Mathematically, it can be expressed as:
\[ a_{\text{relative}} = a_1 - a_2 \]
- Here, \( a_1 \) is the acceleration of the first object, and \( a_2 \) is the acceleration of the second object.

2. **Acceleration Due to Gravity:**
- Both objects are moving under the influence of gravity. The acceleration due to gravity (denoted as \( g \)) acts downwards on both objects.
- Thus, for both objects:
\[ a_1 = g \quad \text{and} \quad a_2 = g \]

3. **Calculating Relative Acceleration:**
- Substituting the values of \( a_1 \) and \( a_2 \) into the relative acceleration formula:
\[ a_{\text{relative}} = g - g = 0 \]
- This shows that the relative acceleration between the two objects is indeed zero.

4. **Direction of Acceleration:**
- The reason states that the acceleration of objects under the effect of gravity is always directed downwards and does not depend on the size or mass of the objects.
- This is a fundamental principle of physics; all objects in free fall experience the same acceleration due to gravity, regardless of their mass.

5. **Conclusion:**
- Since both the assertion (A) and the reason (R) are correct and the reason correctly explains the assertion, we conclude that both statements are true.

### Final Answer:
Both the assertion (A) and the reason (R) are correct. Therefore, the correct option is that both A and R are true, and R is the correct explanation of A.

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