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 it does not have a direction associated with it. For example, we can say the temperature is 25 degrees Celsius, but we cannot say it is "25 degrees Celsius to the north." - **B. Speed**: - Speed is also a scalar quantity. It measures how fast an object is moving, but it does not indicate the direction of that movement. For instance, if a car is traveling at 60 km/h, we know its speed, but not the direction it is heading (north, south, etc.). - **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, we have both the size of the force (10 N) and the direction (east). This is crucial in physics because the effect of a force can change depending on its direction. - **D. Mass**: - Mass is a scalar quantity. It measures the amount of matter in an object and does not have a direction. For example, an object with a mass of 5 kg has the same mass regardless of its position in space. 3. **Why Other Options Are Incorrect**: - **Temperature (A)**: Lacks direction; it is purely a measure of thermal energy. - **Speed (B)**: While it indicates how fast something is moving, it does not tell us where it is moving. - **Mass (D)**: It quantifies the amount of matter but does not involve direction. ### Formulas and Concepts - **Force** is often calculated using Newton's second law of motion: \[ F = m \cdot a \] where \( F \) is the force, \( m \) is the mass, and \( a \) is the acceleration. Here, both mass and acceleration are involved, but the resulting force is a vector because it has a direction (the direction of acceleration). ### Common Pitfalls - Students often confuse speed with velocity. Remember, velocity is a vector (it includes direction), while speed is just how fast something is moving. - Similarly, mass and weight are sometimes mixed up. Weight is a force (a vector) that results from the gravitational pull on an object, while mass is a scalar. ### Revision Summary - **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 distinction between scalars and vectors is crucial in physics for solving problems accurately.