Statement`-1:` The work done by all forces on a system equals to the change in kinetic energy of that system . This statement is true even if nonconservative forces act on the system.
Statement `-2:` The total work done by internal forces may be positive.

Options

A. Statement `-1` is True, Statement `-2` is True, Statement`-2` is a correct explanation for Statement`-1`
B. Statement `-1` is True, Statement `-2` is True, Statement`-2` is NOT a correct explanation for Statement`-1`
C. Statement`-1` is True, Statement`-2` is False.
D. Statement`-1` is False,Statement`-2` is True.

Explanation

To analyze the statements given in the question, we will evaluate each statement separately and determine their validity.

### Step 1: Evaluate Statement 1
**Statement 1:** The work done by all forces on a system equals the change in kinetic energy of that system. This statement is true even if non-conservative forces act on the system.

- According to the work-energy theorem, the work done by all forces acting on an object (including both conservative and non-conservative forces) is equal to the change in kinetic energy of that object. This means that even if non-conservative forces (like friction or air resistance) are present, the total work done on the system will still equal the change in kinetic energy.

**Conclusion for Statement 1:** This statement is true.

### Step 2: Evaluate Statement 2
**Statement 2:** The total work done by internal forces may be positive.

- Internal forces are the forces that the objects in a system exert on each other. The work done by internal forces can indeed be positive, negative, or zero, depending on the nature of the forces and the displacement of the objects involved. However, the statement claims that it "may be positive," which is a true statement since internal forces can do positive work in certain scenarios (e.g., when two objects in a system push each other apart).

**Conclusion for Statement 2:** This statement is also true.

### Step 3: Determine the Relationship Between the Statements
Now that we have established that both statements are true, we need to determine if one explains the other.

- Statement 1 explains the relationship between work done by all forces and the change in kinetic energy.
- Statement 2, while true, does not provide an explanation for Statement 1. It simply states a condition about internal forces.

**Final Conclusion:** Both statements are true, but Statement 2 does not explain Statement 1.

### Summary of the Solution:
- **Statement 1:** True (Work done by all forces equals change in kinetic energy, even with non-conservative forces).
- **Statement 2:** True (Total work done by internal forces can be positive).
- **Explanation Relationship:** Statement 2 does not explain Statement 1.