The correct option is **C. Force**. ### Detailed Explanation 1. **Understanding Scalars and Vectors**: - In physics, quantities are classified into two categories: scalars and vectors. - **Scalars** are quantities that have only magnitude (size) and no direction. Examples include temperature, speed, and mass. - **Vectors**, on the other hand, have both magnitude and direction. Examples include force, velocity, and displacement. 2. **Analyzing Each Option**: - **A. Temperature**: - Temperature is a scalar quantity. It tells us how hot or cold something is but does not have a direction associated with it. For example, saying the temperature is 30 degrees Celsius does not imply any direction. - **B. Speed**: - Speed is also a scalar quantity. It measures how fast an object is moving, expressed in units like meters per second (m/s). For instance, if a car is traveling at 60 km/h, it indicates the rate of motion but does not specify the direction of travel. - **C. Force**: - Force is a vector quantity. It has both magnitude and direction. For example, if a force of 10 Newtons is applied to the east, it is not just about how strong the force is (10 N) but also where it is applied (to the east). This directional aspect is crucial in understanding how forces interact with objects. - **D. Mass**: - Mass is a scalar quantity. It measures the amount of matter in an object and is expressed in kilograms (kg). Mass does not have a direction; it simply tells us how much matter is present. 3. **Why Other Options Are Incorrect**: - Options A, B, and D are all scalar quantities. They lack the directional component that is essential for a quantity to be classified as a vector. - Understanding the distinction between scalars and vectors is fundamental in physics, especially when analyzing motion, forces, and other physical phenomena. ### Common Pitfalls - Students often confuse speed with velocity. Remember, speed is a scalar (no direction), while velocity is a vector (includes direction). - Similarly, mass is often mistakenly thought of as a vector due to its importance in force calculations (F = ma), but it remains a scalar. ### Summary for Revision - **Scalars** have only magnitude (e.g., temperature, speed, mass). - **Vectors** have both magnitude and direction (e.g., force). - **Force** is the only vector quantity among the options provided. - Understanding the difference between scalars and vectors is crucial for solving physics problems effectively.