Newton s first law defines

Options

A. force only
B. inertia only
C. both force and inertia
D. Neither force nor inertia

Answer

**Step-by-Step Solution:**

1. **Understanding Newton's First Law**:
Newton's first law of motion states that an object will remain at rest or in uniform motion in a straight line unless acted upon by a net external force. This means that if no net force is acting on an object, it will not change its state of motion.

2. **Identifying Key Concepts**:
The key concepts in Newton's first law are:
- **Inertia**: The tendency of an object to resist changes in its state of motion.
- **Force**: An external influence that can change the motion of an object.

3. **Analyzing the Options**:
The question provides four options:
- Force
- Energy
- Both Force and Energy
- Neither Force nor Energy

4. **Evaluating Each Option**:
- **Force**: Newton's first law directly relates to force as it describes how an external force is necessary to change the motion of an object.
- **Energy**: While energy is related to motion (kinetic energy) and rest (potential energy), Newton's first law does not explicitly define energy.
- **Both Force and Energy**: Since energy is not explicitly defined in the law, this option is incorrect.
- **Neither Force nor Energy**: This option is also incorrect as the law does define the concept of force.

5. **Conclusion**:
Based on the analysis, Newton's first law primarily defines the concept of **force** and the property of **inertia**. Therefore, the correct answer is that it defines **force** and **inertia**.

**Final Answer**: Newton's first law defines both force and inertia.

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