General physicsLesson 2 of 4 in the course Kinematics

Scalars, Vectors, and One-Dimensional Coordinate Signs

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson explains how vectors differ from scalars and how to choose a coordinate system for describing one-dimensional motion. These ideas are essential in kinematics because motion descriptions often require both an amount and a direction.

A scalar is a quantity with magnitude only. Magnitude describes an amount or size; a scalar has no specified direction. Examples include distance, speed, temperature, energy, and height. A distance of 2.0 m2.0\text{ m} and a speed of 90 km/h90\text{ km/h} are scalars because neither identifies a direction.

All flashcards

What is a scalar?
A scalar is a physical quantity with magnitude but no specified direction. Distance, speed, temperature, and energy are examples.
What is a vector?
A vector is a physical quantity with both magnitude and direction. Displacement, velocity, and force are examples.
How do distance and displacement differ?
Distance is the total length of the path traveled and is scalar. Displacement is the directed change from the starting position to the ending position and is vector.
How does an arrow represent a vector?
The arrow points in the vector’s direction, and its length is proportional to the vector’s magnitude according to the diagram’s scale.
What must you do when assigning a one-dimensional coordinate system?
Choose one direction as positive, treat the opposite direction as negative, and keep the choice clear and consistent throughout the problem.

Quiz questions

  1. What distinguishes a vector from a scalar?Answer: A vector has magnitude and direction; a scalar has magnitude only.
  2. Which quantity is a scalar?Answer: A distance of 2.0 m2.0\text{ m}
  3. A person walks 3 m3\text{ m} east and then 3 m3\text{ m} west. What are the total distance and displacement?Answer: The distance is 6 m6\text{ m} and the displacement is zero.
  4. If right is defined as positive, what does a negative displacement indicate?Answer: It points left, opposite to the chosen positive direction.
  5. Why might downward be chosen as positive when analyzing a falling object?Answer: It may simplify the description if used consistently.

Based on College Physics 2e by Paul Peter Urone, Roger Hinrichs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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