The correct option is **C. Force**. ### Detailed Explanation In physics, quantities can be classified into two main categories: **base quantities** and **derived quantities**. 1. **Base Quantities**: These are fundamental physical quantities that cannot be expressed in terms of other quantities. They serve as the foundation for measuring physical phenomena. The International System of Units (SI) defines seven base quantities, which include: - Length (meter, m) - Mass (kilogram, kg) - Time (second, s) - Electric current (ampere, A) - Temperature (kelvin, K) - Amount of substance (mole, mol) - Luminous intensity (candela, cd) 2. **Derived Quantities**: These are quantities that are derived from the base quantities through mathematical relationships. They are expressed in terms of the base quantities. For example: - **Force** is defined by Newton's second law of motion, which states that force equals mass times acceleration (F = ma). Here, force is derived from the base quantities of mass (kg) and acceleration (m/s²). Now, let’s analyze the options provided: - **A. Length**: This is a base quantity. It is one of the fundamental measurements in physics and is not derived from other quantities. - **B. Mass**: This is also a base quantity. It represents the amount of matter in an object and is measured in kilograms (kg). - **C. Force**: This is the correct answer. As mentioned, force is derived from the base quantities of mass and acceleration. The formula for force (F = ma) shows that it is not a fundamental measurement but rather a combination of other measurements. - **D. Time**: This is another base quantity. It measures the duration of events and is fundamental to the study of motion and change. ### Why Other Options Are Incorrect - **Length (A)**: As a base quantity, length is fundamental and does not depend on other measurements. It is measured in meters (m) and is essential for defining other derived quantities, but it itself is not derived. - **Mass (B)**: Similar to length, mass is a base quantity. It is a measure of the amount of matter in an object and is not derived from any other quantities. - **Time (D)**: Time is also a base quantity. It is a fundamental aspect of physics that measures the progression of events and is not derived from other quantities. ### Common Pitfalls - Students often confuse derived quantities with base quantities, especially when they involve familiar concepts like force, which is commonly encountered in physics problems. - It’s important to remember that derived quantities are formed through relationships involving base quantities, so understanding the definitions and relationships is crucial. ### Revision Summary - **Base quantities** are fundamental measurements (e.g., length, mass, time) that cannot be derived from other quantities. - **Derived quantities** are formed from base quantities through mathematical relationships (e.g., force = mass × acceleration). - **Force** is a derived quantity, while length, mass, and time are base quantities. - Understanding the distinction between base and derived quantities is essential for solving physics problems effectively.