Posted by **Belinda** on Friday, October 21, 2011 at 11:22am.

I am given two points on an acceleration vs time graph: (-2,13),(4,0). When t = -2s, v = 10 m\s. What velocity at t = 6s? I believe acceleration average is (-13/6), but how do I solve the rest get the correct answer, which is 44.7 m/s? Any help or hints would be greatly appreciated.

- Physics - acceleration..need to find velocity -
**Steve**, Friday, October 21, 2011 at 1:14pm
If v=10 when t= -2, and you have negative acceleration, v is decreasing. How can it increase to 44.7? Is there a typo in here somewhere?

- Physics - acceleration..need to find velocity -
**Steve**, Friday, October 21, 2011 at 1:25pm
Never mind. I see acceleration is not constant.

However, I get 15.3 m/s. I will have to recheck my math.

- Physics - acceleration..need to find velocity -
**Steve**, Friday, October 21, 2011 at 6:48pm
OK. Finally got a moment,

If we assume a linear function for acceleration, and fitting it to the two points, we get

a = -13/6 t + 26/3

v = V_{0} + 26/3 t - 13/12 t^{2}

v(2) = 10 = V_{0} - 26/3 * 2 - 13/12 * 4

10 = V_{0} -65/3

V_{0} = 95/3

So, now we know

v(t) = 95/3 + 26/3 t - 13/12 t^{2}

v(6) = 95/3 + 26/3 * 6 - 13/12 * 36 = 44 2/3 = 44.7

- Physics - acceleration..need to find velocity -
**Anonymous**, Wednesday, September 4, 2013 at 11:46pm
An autos velocity increases uniformly from 6m/s to20m/s while covering 70m.find the acceleration and the time taken.

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