Motion

Which way did it go?

What is Motion?

• Motion occurs when an object changes position over time.

http://rsd.gsfc.nasa.gov/rsd/images/andrewSequence_lg.jpg

Speed

• Speed is the rate at which an object moves.

• Speed depends on distance and time.

• Speed is measured in meters per second m/s, km/hr, mi/hr.

http://www.blogfunny.com/media/snail%20speeding.jpg

http://www.visitthedot.com/images/about/racing%20-%20blurred%20cars.jpg

Calculating Average Speed

• Average speed is calculated by dividing total distance by total time taken.

• Avg. speed = total distance/total time

http://www.stvincent.ac.uk/Resources/Physics/Speed/speed/definitions.html

Examples

• You traveled 20 miles on your bike. It took you a total of 4 hours. What was your average speed?

• You walked 6 miles to your friends house and it took you 2 hours to get there. What was your average speed?

Velocity

• Velocity is the speed of an object in a particular direction.

• Speed and velocity do not mean the same thing because velocity includes a direction.

• Velocity changes as speed or direction changes.

http://www.stvincent.ac.uk/Resources/Physics/Speed/speed/images/fighters.gif

Examples

• 60 mph – Speed

• 60mph North – Velocity

• 70mph – Speed

• 70 mph Southeast - Velocity

Acceleration

• Acceleration is the rate at which speed changes.• Acceleration is calculated by the following formula:

• Acceleration = final speed – initial speed / time    • Acceleration is measured in meters per second

squared ((m/s)2)

http://www.glenbrook.k12.il.us/gbssci/Phys/mmedia/kinema/acceln.htmlhttp://www.stvincent.ac.uk/Resources/Physics/Speed/speed/formulae.html

Examples

• While drag racing out of our school parking lot, I time myself at a speed of 40 meters per second seven seconds after starting. What was my acceleration during this time?

• While running away from the school building on a Friday afternoon, my speed increases from 5.0 m/s to 7.5 m/s over a period of 1.25s.  What is the my average acceleration during this period?

Examples of Acceleration

• Acceleration in which speed increases is called positive acceleration.

• Acceleration in which speed decreases is called negative acceleration.

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http://discover.edventures.com/images/termlib/d/deceleration/support.gif