MOTIONDescribing & Measuring Motion

Recognizing Motion

Motion The state in which

one object’s distance from another is changing.

Even though you are sitting still right now you are actually moving 30 kilometers every second

Whether an object is moving or not depends on your POINT OF VIEW.

Unit of Force = Newtons (N)

Recognizing Motion Reference Point

A place or object used for comparison to determine if something is in motion.

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

You assume that the reference point is stationary, or not moving, however it is also in motion.

Describing Distance To describe motion

further, you need to use units of measurements. 2 cups of milk Run 100 yards Buy 3 pounds of fruit

International System of Units (SI) A system of

measurement based on multiples of ten and on established measures of MASS, LENGTH, and TIME.

To help communicate information clearly scientists all over the world use them same system of units.

Describing Distance Meter

Basic SI unit of length

SI units area also used to describe quantities such as volume (liter-L) and mass (grams-g)

Calculating Speed

Speed The distance an object

travels in one unit of time.

Constant Speed Movement at a fixed

(constant) distance per unit of time.

Average Speed Total distance covered

over a time interval.

Calculating Speed

Average Speed Examples

A cyclist changes their speed many times during a race. Climb up steep inclines, glide alone level ground, dash down hills, etc.

A racecar driver changes speed many times during a race. Around sharp corners, straight a ways, pit stops, etc.

You find the average speed by adding up the speeds and adding up the times and then divide the two #’s.

Most objects do not travel at a constant speed very long.

Constant Speed Examples

A ship traveling across the ocean may move at the same speed for several hours.

A horse cantering across a field may keep at a steady pace for several minutes.

Anything that travels at a speed that doesn’t change is traveling at a constant speed.

The speed is always the same at all times during motion.

Describing Velocity It is important to not only know the speed of things but also

direction

Velocity When you know both speed in direction of an objects motion.

Air traffic controllers must know the velocity of aircrafts

Forecasters must the velocity of thunderstorms, snowstorms, etc.

Stunt pilots use velocity to prevent collisions and make graceful maneuvers

Describing Velocity

Benz Tricycle Car 15 km/h

Transcontinental Railroad 30 km/h

Interstate Highway System 100 km/h

TGV in Motion 300 km/h

Ford Model T 65 km/h

Pioneer Zephyr 125 km/h

Graphing Motion

You represent motion with a line graph. Y-axis = distance X-axis = time

Each point on the graph represents the location of the object at a particular time.

A straight line (a line with a constant slant, or slope) represents motion at a constant speed.

The steepness of the slope depends on how quickly or slowly the object is moving.

The faster the motion, the steeper the slope.

A horizontal line represents an object that is not moving at all.