1. DO NOW: Have filmstrip and questions out on your desk.
Open your textbooks to page 16. Open your notebooks.
Chapter 1 Quiz: Tuesday, Feb 7th

2. Speed measures how fast position changes
Chapter 1.2

3. Speed the rate at which an object moves
a measure of how fast something moves, or the distance it moves, in a given amount of time

4. Speed
a measure of how fast something moves, or the distance it moves, in a given amount of time
Formula:
typically expressed in units of m/s
is considered average when taking into account the total distance covered and the total time of travel
is considered constant when it does not change
is considered instantaneous when it represents a specific instant in time
S = d t
00:00. 4 5 3 1 2 6
What is the ball’s speed?
6 meters

5. Average speed Speed is usually NOT CONSTANT. Examples:
Cars stop and go regularly
Runners go slower uphill than downhill
Average speed = total distance traveled/total time it took

6. Interesting Speeds meters/second miles/hour Cockroach Kangaroo Cheetah
1.25
2.8
Kangaroo 15 34
Cheetah 27 60
Sound
(in 200C air)
343
767
Space Shuttle
(getting into orbit)
7,823
17,500
Light
300,000,000
671,080,888

7. The Speed Triangle
S = d t
t = d S
d = S t . d d S t S . t

9. Practice Problems - Speed
If you walk for 1.5 hours and travel 7.5 km, what is your average speed?
2. Calculate the speed of a bee that flies 22 meters in 2 seconds.
S = d t
7.5 km
5 km hr
S = =
1.5 hr
22 m
11 m
sec
S = d t
S = =
2 sec