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Motion. Describing Motion . An object is in motion if the distance from another object is changing. A reference point is the starting point you choose to describe the location, or position of an object. Position is an object’s distance and direction from a reference point.
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Describing Motion • An object is in motion if the distance from another object is changing. • A reference point is the starting point you choose to describe the location, or position of an object. • Position is an object’s distance and direction from a reference point.
Distance vs. Displacement • Displacement is the difference between the initial (first) position and the final position of an object. • Distance is the length traveled. 45m 45 m Distance = 90 m Displacement = 0 m
Speed • Constant Speed = speed stays the same • Instantaneous Speed = speed at a specific instant in time. • Speed changes when: you slow down you speed up you stop
Velocity • Velocity is the speed AND direction of a moving object. • Velocity changes when: speed changes direction changes both change
Speed & Velocity Formulas • Speed = Distance Time • Average Speed = Total Distance Total Time • Distance = Speed X Time • Time = Distance Speed
Practice Problems • A mail truck takes 20 s to move between mailboxes that are 10 m apart. What is the average speed of the mail truck? • Sound travels 330 m/s. You hear the sound of the bat hitting a home run 0.5 s after you see it. How far away are you? • Steve swims 10 m in 20 s. What is his average speed?
Two cities are 250 km apart. How much time will it take to travel from one city to the other at 100 km/h? • If a train travels 120 km at 30 km/h, how long will it travel? • An eagle flies 300 m in 12 s, what was its average speed?