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Learn about the differences between scalars and vectors in energy and motion and how they are used to describe speed, distance, velocity, and displacement.
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Communicating about Motion • Your friend invites you over after school and says his house is 1.2 Km away and if you walk at a pace of 4km/hr it should take you 15 minutes. Would you know how to get there?
Scalars and Vectors Scalar: Quantities that describe magnitude but NOT direction Ex: speed, distance, time Vectors: Quantities that DO include direction Ex: velocity, displacement
Distance and Displacement Distance: a scalar quantity that describes a length of a path between two points Variable – Δd Unit – Km, m, cm Example – I walked 152 km Displacement: a vector quantity that describes a length of a path but includes DIRECTION Variable – Δd Example – I walked 152 Km North
Formula for Displacement: Δd = d2 – d1 Δd = displacement d1 = initial or starting position d2 = final or ending position
Speed and Velocity: Speed – scalar Velocity – Vector Formula: Velocity(m/s) = distance (m) v = Δd time (s) Δt
Example #1: Ms Schmalenberg runs at a velocity of 29 m/s N. If it runs for 8.4 seconds what is her displacement? v = 29m/s(N) v = d d = vt t= 8.4 s t d = ? d = (29m/s(N))(8.4s) d = 2.4 x 102
Example #2: A car has a speed of 67Km/hr and travels a distance of 4500 meters. How long did it take the car to travel this distance? v = 67 km/hr OR 18.6 m/s v = d t = d d = 4500 m OR 4.5 km t v t = ? t = 4500m t = 240s 18.6m/s
Graphing Velocity: • Title • Draw and label x and Y axis(include units) • Create a scale on axis • Plot points • Draw a line of best fit • Calculate Slope
Negative vs Positive Acceleration Positive and a positive = positive Positive and a negative = negative Negative and a positive = negative Negative and a Negative = positive
Formula: Acceleration = velocity a = Δv time Δt Units: Rearrangements: a = m/s2 v = at t = v v = m/s a t= s
Example Ms Schmalenberg reached a speed(running) of 19 m/s from a starting point in a period of 2.0 seconds. What is her acceleration going east of her starting point? v = 19m/s a = v a = 19m/s t = 2.0 s t 2.0 s a = ? a = 9.5 m/s2
Portfolio Assignment #5 Pg 192 # 23-31