2 Key Concepts and Vocabulary What is needed to describe motion completely?How are distance and displacement different?How do you add displacements?Vocabulary:Frame of ReferenceRelative MotionDistanceVectorResultant Vector
3 Distance Length of a path between two points. Units: kilometers, meters, centimeters
4 DisplacementDirection from the starting point and the length of a straight line from the starting point to the ending point.
5 Displacement Along A Straight Line 20km30km15km1020304050607080Displacement = 20 km + 30 km + 15 km = 65 km east-10km30km30km1020304050607080Displacement = 40 km km + 40 km = 70 km east
6 Vector Vector is a quantity that has magnitude and direction 12 km northwestMagnitude – size, length, or amountLength of arrows shows the magnitude
8 Displacement That Isn’t Along a Straight Line When two or more displacement vectors have different directions, they can be combined by graphing.
9 Based on the red arrows, how far did Mrs. Ewald walk? Add the magnitudes of each vector along the path.2 long blocks south2 short blocks east1 long block south3 short blocks eastTotal = 8 blocksor11 short blocksPath walked by Mrs. Ewald1 long block = 2 short blocks
10 Based on the red arrows, how far did Mrs. Ewald walk? The vector in yellow is the resultant vector – vector sum of two or more vectors.Points directly from start to finish.Resultant vector = 8 short blocksPath walked by Mrs. Ewald
11 Question? Mrs. Ewald walks 4m east, 2m south, 4m west, and 2m north. What is the total distance Mrs. Ewald walked?What is the total displacement?4m + 2m + 4m + 2m = 12mDisplacement = 0m2m4m
21 Key Concepts and Vocabulary How are changes in velocities described?How can you calculate acceleration?Vocabulary:AccelerationFree Fall
22 AccelerationA vector described as a changes in speed, changes in direction, or changes in both.Change in SpeedFree fall (9.8 m/s2)Change in DirectionRiding a merry-go-roundChanges in Speed and DirectionSpeeding up around a corner
23 Calculating Acceleration Equation:Acceleration = Change in VelocityTimeAcceleration = Velocityfinal – Velocityinitiala = vf – vitUnit of Measure: m/s2, km/s2
24 ExampleA car travelling at 10 m/s starts to slow down steadily. It comes to a complete stop in 20 seconds. What is its acceleration?
25 ExampleAn airplane travels down a runway for 4.0 seconds, with an acceleration of 9.0 m/s2. What is its change in velocity during this time?
26 ExampleA child drops a ball from a bridge. The ball strikes the water under the bridge 2.0 seconds later. What is the velocity of the ball when it strikes the water?
27 ExampleA boy throws a rock straight up into the air. It reaches the highest point of its flight after 2.5 seconds. How fast was the rock going when it left the boys hand?