Average Velocity Graph: Determine its Values

[Toxage]

Graph :

http://img354.imageshack.us/my.php?image=physicslp1.png

or

http://www.turboimagehost.com/p/766378/physics.JPG.html

Questions:

Determine its average velocity between the following times.

1. t = 25.0 s and t = 30.0s

2. t = 35.0 s and t = 50.0 s

The Attempt at a Solution

average velocity = overall displacement / overall time

1. 6m/5 sec = 1. m/s

2. 10 m / 15 s = 2/3 ms

My teacher uses on online homework program called Webassign, and both of these showed up as wrong. I don't know why. If anyone could help me that would be awesome.

 

[LowlyPion]

Graph :

http://img354.imageshack.us/my.php?image=physicslp1.png

or

http://www.turboimagehost.com/p/766378/physics.JPG.html

Questions:

Determine its average velocity between the following times.

1. t = 25.0 s and t = 30.0s

2. t = 35.0 s and t = 50.0 s

The Attempt at a Solution

average velocity = overall displacement / overall time

1. 6m/5 sec = 1. m/s

2. 10 m / 15 s = 2/3 ms

My teacher uses on online homework program called Webassign, and both of these showed up as wrong. I don't know why. If anyone could help me that would be awesome.

On the first it looks like 8m not 6m. It will likely not think it's good if off by 10%.

Check your sign on the second one.