Which of the following quantities is a vector?
Select one: a. time b. force C energy d. speed
The correct answer and explanation is:
The correct answer is b. force.
To explain why, it is important to understand the difference between vector and scalar quantities. A vector is a physical quantity that has both magnitude and direction. In contrast, a scalar quantity only has magnitude and no direction.
- Time (a) is a scalar quantity. It has only magnitude and does not depend on direction.
- Force (b) is a vector quantity. Force has both magnitude (how strong the force is) and direction (where the force is applied). For example, when you push a car, the force has a direction in which you apply the push.
- Energy (c) is a scalar quantity. Energy measures how much work is done or potential to do work, and it does not involve any direction.
- Speed (d) is also a scalar quantity. Speed measures how fast an object moves, but it does not specify the direction in which the object is moving. If you add direction to speed, it becomes velocity, which is a vector.
The key feature of force that makes it a vector is its dependence on both magnitude and direction. This is why it is often represented by arrows where the length of the arrow shows how strong the force is, and the arrowhead points in the direction of the force. Understanding that a vector quantity requires both magnitude and direction, force clearly fits into this category.