Assign the proper sign to q and w in the following cases :
15 kJ of energy is transferred to the system by doing work on it.

Explanation

To solve the problem of assigning the proper signs to \( q \) (heat) and \( w \) (work) in the given scenario, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Energy Transfer**: The problem states that 15 kJ of energy is transferred to the system by doing work on it. This indicates that energy is being added to the system.

2. **Determine the Sign of \( q \)**:
- In thermodynamics, when heat enters the system, it is assigned a positive sign.
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