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emery-gibson
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Motion!
Key Ideas
An object in motion changes position.
Speed measures how fast position changes.
Acceleration measures how fast velocity changes.
Position Position = location of a place or object Reference Point = location to which
you compare other locations You need a reference point to describe
a location.
Examples: Tyler is sitting next to Sarah. Santiago, Chile is about 3000km southwest
of Brasilia, Brazil.
Latitude and Longitude
Distance
May be straight-line length or length of a path or route
Standard unit of measure is meters (m) Longer distances use kilometers (km) Shorter distances use centimeters
(cm)
From Hickory to Holly Ridge
Straight-line distance: 373 km (232 mi)
Travel distance: (307 mi)
Motion
Motion = a change in position over time
A change in position is evidence that motion has happened
Relative Motion How you see an object’s motion
depends on your own motion. http://www.youtube.com/watch?v=
7gu1XDGSbe8 Which direction is the corvette
moving in relation to the mustang? Which direction is the mustang
moving in relation to the corvette?
Speed Speed = measure of how fast
something moves, or the distance it moves in a given amount of time
Greater the speed, faster object changes position
Speed = distance/time, S = d/t Meters per second – m/s Kilometers per hour – km/h
Average Speed
Speed is not constant Calculate speed over a specific
distance Example = time each lap and add
those times together, then average
Distance-Time Graphs
Shows how distance and speed change over time
Plots distance an object travels against the time
Velocity Velocity = speed in a certain direction Changes in direction or speed change
velocity Examples:
Does a car traveling west at 100 km/hr have the same velocity as a car traveling east at 100 km/hr?
Does a car traveling east at 100 km/hr have the same velocity as a car traveling east at 75 km/hr?
Vector
Vector = a quantity that has both size and direction
Velocity is a vector because it has a size (speed) and a direction
Velocity vs. Speed Walking north from home to the
store you travel at a speed of 5 km/h.
Walking south back home from the store you travel at the same speed of 5 km/hr.
Speed is still 5 km/hr But velocity is 0 km/hr because
you ended up where you started!
Acceleration
Acceleration = rate at which velocity changes
Types of Acceleration
In same direction as motion Speeding up
In opposite direction of motion Negative acceleration, slowing
down At a right angle to motion
Change direction but speed is the same
Formula for Acceleration
Velocity-Time Graph