Welcome Physicists! DQ: Mrs. Ellis drove to work this morning from Woodburn through Oregon City. The distance was 20.5 miles and it took about 35 minutes. Calculate Mrs. Ellis’s velocity. v = distance How fast would that be in miles per hour? Did Mrs. Ellis break the speed limit? time

Average Velocity Do you think the velocity you calculated was the exact speed that Mrs. Ellis was driving at every minute? Of course you don’t, because you’re smart that way What you calculated was average velocity – – As if you could take all the different velocities Mrs. Ellis was going and find the average The velocity she was driving at any one time is called her instantaneous velocity

Things to remember about velocity: v = distance = d/t Units of distance and time are important! Always write them! Example: if I ran 1000 m in 3.06 minutes, not only would I have been a world record holder in 1916, but my velocity would be v = 1000meters/3.06 minutes = meters per minute If I only write my answer is meaningless time

Another thing Think about what meters/minute means Is this average velocity or instantaneous velocity? Was I going this velocity for the entire race? How far did I go in 1 minute? 2 minutes? How far would I go in an hour? – Could I continue at that rate for an hour? How fast is that in something we can understand? 1000 meters is about 0.62 miles How many miles per minute was I going?

v = distance = d/t v = 0.62 miles/ 3.06 minutes v = 0.2 miles/minute What is that in miles per hour? Well… if there are 60 minutes in an hour and I go 0.2 miles in ONE minute, then I will go… 12miles in one hour = 12m/h time

And now for something (not) completely different Take out a piece of paper Observe the demonstration Describe the energy transformations you observed. BE SPECIFIC! ENERGY TRANSFORMATION PROJECT – Begin today – Continue next week during the first lesson – DUE Monday, October12 (Tuesday 10/13 for 7 th Period)