So if you we're to be given a graph with the slope, how do you find the average velocity from it? Also, what is velocity at halftime? Thanks!

The lawnmower moved at a constant speed of 2 m/s for 60 seconds and at 1 m/s for 120 seconds. Determine the average speed of the lawnmower.

how do you find the net force when the velocity is not constance meaning that acceleration is not zero a= .3 m/s2 m=15kg

The centripetal force on a 0.82 kg object on the end of a 2.0 massless string being swung in a horizontal circle is 4.0 N. What is the tangential velocity of the object? The answer I got is 3.1 m/s squared but I don't know how to show the work for it. So please help me.

http://i927.photobucket.com/albums/ad115/dportal2006/scan0001.jpg This link has the exact graph that relates to my question. I have tried answering the question however, the formula that is provided in my book for instantaneous velocity is change of V/change of t as the limit of t approaches...