Motion

Warm up day 20 (do this on page 20 of notebook) speed=distance time 1. How fast are you going if you cover 13meters in 4seconds? 2. How far will you go if you travel at a speed of 6meters/second for 0.75seconds 3. How long will it take you to travel 5meters at a speed of 3meters per second?

Speed a measure of how fast something moves, the distance it moves, in a given amount of time Formula: in physics, we use the units of meters/second Speed = distance time 00:00. 4 5 3 1 2 6 What is the ball’s speed? 6 meters

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

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

On page 21 write down the following title Graphical Representation of Motion Motion can be described using graphs Distance/time graphs

Distance-Time Graph Shows how speed relates to distance and time D 50 40 30 20 10 60 70 80 90 100 Time (seconds) 120 Distance (meters) D This distance-time graph will show a student’s speed as s/he returns to class after lunch. What is the speed from C-D ? What is the speed from B-C ? B C What is the student’s average speed? What is the speed from A-B ? A

Follow along and write down examples from the board

Describe What’s Happening (distance-time graphs) Constant speed; away from starting point Constant speed; no movement Constant speed; toward the starting point

Complete the speed problems on your own See Handout. Add this to problem list: A student walks 5 meters down the hall in 4 seconds. The student then stops for 4 seconds. Then student then returns to where she started in 4seconds. Draw a distance/time graph that shows this motion.