# Finding average acceleration over an time interal

## Homework Statement

An object moving with a constant acceleration travels 13 m in 7.8 s. The acceleration is then changed and the object covers an additional 34 m in 1.7 s. What is the average acceleration of the object over the entire interval described?

## Homework Equations

Xf1 = 1/2(vo +vf)t
a=(vo +vf)/t

## The Attempt at a Solution

vf1 =2(13)/7.8
vo =2(34)(1.7) - 44.2
a = (115.6-44.2)9.5

im not sure how to solve this problem

take it back to orginial equation... you can not break down like that...
here is my answer for you: 0.52m/s/s (starting at 0)
however please consider the starting speed...

can you show me what equation u used?

lol, this has nothing to do with acceleration equation...
you just simply add 2 total distance together and divid them by total time to get average v, then v/t=a

if u add the total distance and time, you only get an average velocity of one interval. The motion changes velocity.

do you mean average accerleration over entire time or something else? i am not quit getting it...

average acceleration over the entire interval

then my answer should be right...

you said average...

i solved it. by finding the first velocity d/t. then the second velocity is 2(d2/t2) - v1. then acceleration is vf - vo over time

dude i told you....