At a certain time a particle had a speed of 80 m/s in the positive x direction, and 7.0 s later its speed was 90 m/s in the opposite direction. What was the average acceleration of the particle during this 7.0 s interval?

I can think of two answers that I could get:
24.29m/s^2
1.43 m/s^2

Any help would be appreciated.

Question

At a certain time a particle had a speed of 80 m/s in the positive x direction, and 7.0 s later its speed was 90 m/s in the opposite direction. What was the average acceleration of the particle during this 7.0 s interval?

I can think of two answers that I could get:
24.29m/s^2
1.43 m/s^2

Any help would be appreciated.

anonymous · Answer

I got 24.29 too but I haven't done these kind of problems in a long time. I just looked at the change of speed ( so from 80 to 0  and 0 to 90 considering it is in the opposite direction). So I put the acceleration as 24.28. ^^ ( well a = speed / delta t

anonymous · Answer

or if you want to spend the time on it, draw the graph, find the rule of the velocity graph ( should be a linear one ax+b) and integrate it ^^

austinl · Answer

Ok, thanks! I just wanted another set of eyes to look at it.