Avg velocity = Displacement / Time

[jasoN-]

Average velocity = Displacement / Time


I tried using this on the 2009 exam 2 paper (question 5e section 2) http://www.vcaa.vic.edu.au/vcaa/vce/studies/mathematics/specialist/pastexams/2009/2009specmaths2-w.pdf
I did velocity = displacement / time
=> distance = velocity x time = 4.9 x 180 = 882 [Displacement is the same as distance in this case (the device falls directly vertically downwards).]
My answer was off by 2 metres.


Why doesn't this method work?
I also used Depth = velocity x time for the proceeding questions and yielded incorrect results for (f) but the correct result for (g).

Is it because we are given an instantaneous velocity function and hence can't use it as average velocity?
Help appreciated

[98.40_for_sure]

You mean speed right?
Speed = distance/time    => distance = speed * time

average magnitude of velocity?

[jasoN-]

idk. i found average velocity = (Essentials p389)
just now i also found Average speed = distance travelled / change in time (p390)
now im even more confused

[98.40_for_sure]

Average velocity is displacement/time
average speed is distance/time

The question from vcaa that you're referring to is a speed one.