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

Speed measures how fast position changes Chapter 1.2

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

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

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

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

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

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