1. 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

2. 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

3. 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 slow down turn/change direction
***All of these motions involve acceleration because the velocity changes as time elapses***

4. 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

5. 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

6. 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

7. Sample Problem #1

8. 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 _____.

9. 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

10. 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)

11. 1-4 PTG (p68-71)
8. a) a =
b) vave =
c) d=
9. a) a =
c) vf =

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

13. 1*4 TOTD