# Equations and Time Intervals

• Dec 5th 2011, 06:15 AM
jatt11
Equations and Time Intervals
http://i40.tinypic.com/fsxdw.jpg

I Understand how to graph this one but need help on the Equations and Time Intervals.
• Dec 6th 2011, 02:40 PM
HallsofIvy
Re: Equations and Time Intervals
How could you possibly graph it if you don't know what "equations" and "time intervals" they are talking about. That's all the graph is!

"Santiago starts out by walking at 2 m/s for 2 minutes". Of course to make a graph we have to decide on what points on the graph mean. Taking t (time in seconds) to be the horizontal axis and x (distance walked in meters) as the vertical axis and the beginning point as x= 0, he starts at (0, 0) and after 2 minutes (120 seconds) he will have walked 120(2)= 240 meters so the new point is (120, 240). Since x = 2*t is a linear equation, the graph is the straight line between (0, 0) and (120, 240). Then he waits at the light for 30 seconds. That is, while t goes from 120 to 120+ 30= 150, x stays 240. The graph is a horizontal line between (120, 240) to (150, 240).

At that point he turns around and goes back home at 5 m/s. That is, he went back that original 240 m at 5 m/s which would take him 240/5= 48 seconds. He went from (150, 240) to (198, 0). Draw that line. He bangs on the door for 3 minutes (180 seconds)- from t= 198 to t= 198+ 180= 370 while x stays 0. Draw the line from (198, 0) to (370, 0).

Finally, he runs to school without stopping (hopefully, the traffic light just happened to be green when he got there!) at 4 m/s. We were told that the school is 500 m from his home so that took him 500/4= 125 seconds. Draw the line from (370, 0) to (495, 500).