# Unit 1: Measurement and Motion

The first lab activity associated with this textbook guides you through the process of performing an experiment to determine human reaction time. The experimental setup is similar (but not exactly the same) as seen in this video. Any rigorous scientific experiment requires an understanding of measurement units of measure, and measurement uncertainty (next unit). Preparing the particular setup for this lab also requires and understanding of basic motion concepts such as position, velocity, acceleration, and free-fall. The following chapters in this unit will introduce these concepts. The learner outcomes for this unit are listed below, and below that are some related key terms to watch out for as you complete the chapter.

### Unit 2 Learner Outcomes

- Find necessary conversion factors and convert between SI and non-standard units for several physical quantities. [1]
- Perform order of magnitude estimation. [2]
- Provide definitions for, and describe the connections among, distance, speed, position, displacement, velocity, and acceleration. [2]
- Apply basic kinematics to analyze the motion of objects and model experimental data [3].

Key Terms and Concepts

a system of physical units ( SI units ) based on the meter, kilogram, second, ampere, kelvin, candela, and mole

a number that relates two different units of measure for the same quantity and allows conversion between the two units

the process of approximating a value to obtain a result you expect to at least be within one order of magnitude of the correct answer.

a way of writing very large or very small numbers. A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10.

a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit

distance traveled divided by time during which motion occurs

the location of an object relative to a defined reference point

change in position, typically in reference to a change away from an equilibrium position or a change occurring over a specified time interval

a quantity of speed with a defined direction, the change in speed per unit time, the slope of the position vs. time graph

the change in velocity per unit time, the slope of a velocity vs. time graph

The acceleration of an object when gravity is the only force acting on it. Equal to 9.8 m/s/s near the surface of Earth