Section 4 Graphing Motion: Distance, Velocity, and Acceleration WDYS? 1. 2. 3. WDYT? 1. Similarities: 2. Differences: 1-4 Investigate – use a motion detector to explore motion

Acceleration (p58) EXAMPLE car going down the ramp When things change speed, it is usually noticeable EXAMPLE car going down the ramp Like velocity there are 3 models for looking at acceleration: Particle model Graphing Math

Acceleration is a Vector Quantity (p59) Acceleration means “how fast the velocity changes” EXAMPLE a car can exhibit greater acceleration than a bus, it can go from 0-60mph faster There are 3 ways to change velocity: 1. speed up 2. slow down 3. turn/change direction ***All of these motions involve acceleration because the velocity changes as time elapses***

Acceleration is a Vector Quantity (p59) Positive Acceleration  an increase in velocity, where the final velocity is greater than the initial velocity EXAMPLE a car goes DOWN a ramp Speeding Up Negative Acceleration  a decrease in velocity, where the final velocity is less than the initial velocity EXAMPLE a car goes UP a ramp Slowing Down

Acceleration is a Vector Quantity (p59) Velocity is a Vector Quantity  has both magnitude (size) and direction Speed is a Scalar Quantity  has only magnitude (size), NO direction

Using the Equation for Acceleration (p61-62) *** Speed is ALWAYS changing during constant acceleration*** acceleration = change in velocity / change in time a = ∆ v / ∆ t ∆ v = a × ∆ t ∆ t = ∆ v / a ∆ = final - initial Units for acceleration (a) : km/h/h (km/h2) m/s/s (m/s2) velocity (v) : km/h m/s time (t) : h s

Sample Problem #1

1-4 Checking Up Questions (p64) The equation for acceleration is _____. The SI unit for measuring acceleration is _____. The difference between a vector and a scalar quantity is _____. A d-t graph for constant velocity is: A v-t graph for constant acceleration is: 5. The slope of a v-t graph represents _____.

1-4 Investigate (p52-57) 6a) Draw AND label the d-t and v-t graph from the computer c) d-t graph, slope = _____ d) v-t graph, slope = _____ therefore shows a ______ acceleration

Comparing Motion GRAPHS (p64) Car at REST Car at CONSTANT VELOCITY Car at POSITIVE Acceleration Car at NEGATIVE Acceleration d-t Position does NOT change Position changes at a constant rate; STRAIGHT LINE Speeding up; CURVED LINE Slowing down; CURVED LINE v-t Velocity is ALWAYS ZERO The d-t is constant therefore acceleration is constant Increase in speed, therefore slope is positive (upward) Decrease in speed, therefore slope is negative (down)

1-4 PTG (p68-71) 8. a) a = b) vave = c) d= 9. a) a = c) vf =

1-4 PTG (p68-71) 10. a) b) 12. a) b) c) d) 13. a) a = b) ∆v = 15. a) a =

1*4 TOTD