Measuring Motion

• Recognizing Motion

• Describing Distance

• Calculating Speed

• Average Speed

• Velocity

• Graphing Motion

Recognizing Motion

• Apparent motion-when distance changes you and an object

– Depends on perspective

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

When your standing still…

• Think about this:

• .5km/sec Earth’s Revolution

• 30km/sec Earth’s Rotation

• 230km/sec Solar system

• 600km/sec Galaxy in space

Example

• If two trains are moving by each other at the exact same speed…do they appear to be in motion if the reference point is in one of the trains?

• If two trains are moving by each other at the exact same speed…are they in motion if the reference point is alongside the tracks?

Describing Distance

• Meters (mm-km)

– Distance=length

• What type of meter would you use to measure the width of a penny?

• What type of meter would you use to measure the length of a town?

Calculating Speed

• Speed=Distance over time

• 30mi/hr

• If I traveled 60km in 4 hours…what is my speed?

• If I traveled 800km in 20 hours what is my speed?

Average Speed

• How do we find averages?

• So Mr. H is running from a crowd of angry 6th

graders ;). He hops in his car and travels 40km in the first hour. However, 6th graders are quick and he is soon forced to flee 20km. However, his car has engine trouble and he takes 4 hours to travel 20km. What is the average speed of his journey?

• Mr. G is running. He travels 10km in a half hour. Then rests and travels another 5km in an hour. What is his average speed?

Velocity

• Speed in a given direction

– Need both speed and direction of motion.

– It is possible to have (-) velocity

• Difference between velocity and speed

– 40km/hr = speed

– 40km/hr west = velocity

Graphing Review

• Time (Independent variable) on x-axis

• Distance (Dependent variable) on y-axis

• Make sure there is a title on your graph

Title Graphing Motion Graph Example

Time Distance

1 200m

2 400m

3 400m

4 600m

5 750m