**Motion**

**A. Recognizing
Motion**

**1. An object is in motion
when its distance from another object is changing.**

**2. Movement
is based upon ones point of view based on a reference point.**

**a.
We assume reference points are stationary.**

**b. A reference point
is a place or object used for comparison to determine if something is in motion.**

**c.
An object is in motion if it changes position relative to a reference point.**

**B. Describing Distance**

**1. In science we use the International System of Units (SI) and is based on units
of 10.**

**a. The basic SI unit of length is a meter
(m).**

**b. cm = centimeter: 1/100 of a meter**

**c. mm = millimeter: 1/1000 of a meter**

**d.
km = kilometer: 1000 meters**

**C.
Calculating Speed**

**1.
Speed is a type of rate.**

**2. The speed of an object is the distance the object
travels per unit of time.**

**3. Formula: Speed = Distance / Time**

**4. When the speed of an object does not change, it is known as Constant Speed.**

**5. Constant speed is difficult to maintain. (bike, car, running, walking)**

**6. Average speed (most common) is calculated when constant speeds are not or can not
be maintained.**

**D. Velocity**

**1. When you know both the speed and direction of an object’s
motion, you know the velocity of the object.**

**2. Speed in a given
direction is called velocity.**

**E. Acceleration**

**1.
Acceleration is the rate at which velocity changes.**

**a. Velocity has 2 components: speed and direction. **

**2. Acceleration
changes if**

**a. speed increases**

**b. speed decreases (sometimes deceleration, or negative acceleration)**

**c. direction changes.**

**3. To determine
the acceleration of an object, you must calculate the change in velocity during a unit of time.**

**a. If velocity is measured
in meters / second and time is measured in seconds, the unit of acceleration is meters per second per second.**

**b. This unit is written as
m/s². (meters per second squared)**

**4. To calculate the acceleration, subtract the initial
velocity from the final velocity and divide that by the elapsed time.**

**(Final velocity – initial
velocity) (Vf – Vi)**

----------------------------------- = ---------
= Acceleration

(Final time - initial time) (tf – ti)

**F.
Graphing Motion**

**1.
A motion graph indicates time (x-axis) and distance (y-axis).**

**2. The slope
of the line on a motion (position) graph represents speed.**

** a. If linear,
the speed is constant, or unchanging.**

** b. If the line has more than one slope,
the speed changes. **

** c. If the line is a curve, the speed is uniformly changing
(acceleration).**