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 speed, distance, and temperature. - **Vectors**, on the other hand, have both magnitude and direction. Examples include force, velocity, and displacement. 2. **Analyzing the Options**: - **A. Speed**: Speed is a scalar quantity. It tells us how fast an object is moving but does not provide any information about the direction of that movement. For example, saying a car is moving at 60 km/h does not indicate whether it is going north, south, east, or west. - **B. Distance**: Distance is also a scalar quantity. It measures how much ground an object has covered during its motion, regardless of the direction. For instance, if a person walks 5 kilometers, that is the total distance traveled, without any reference to the path taken. - **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 right, it is not just the size of the force that matters, but also the direction in which it is applied. This is crucial in determining how an object will move according to Newton's laws of motion. - **D. Temperature**: Temperature is a scalar quantity. It indicates how hot or cold an object is, measured in degrees Celsius, Fahrenheit, or Kelvin, but it does not have a direction associated with it. 3. **Why Other Options Are Incorrect**: - **Speed (A)** and **Distance (B)** are both scalar quantities, which means they lack directional information. This is a fundamental distinction that makes them different from vector quantities. - **Temperature (D)** is also a scalar quantity, as it only provides a measure of thermal energy without any directional component. ### Common Pitfalls - Students often confuse speed with velocity. Remember, velocity is a vector because it includes direction (e.g., 60 km/h north), while speed does not. - It’s important to remember that while distance and displacement may seem similar, displacement is a vector because it considers the shortest path between two points and includes direction. ### Summary - **Force is a vector quantity** because it has both magnitude and direction. - **Speed, distance, and temperature are scalar quantities**; they only have magnitude and no direction. - Understanding the difference between scalars and vectors is crucial in physics, especially when analyzing motion and forces. ### Revision Summary - Scalars have magnitude only; vectors have both magnitude and direction. - Force is a vector; it requires both size and direction for complete understanding. - Speed, distance, and temperature are scalars; they do not involve direction. - Always clarify whether a quantity is scalar or vector when solving physics problems.