Constant acceleration in a straight line with variable distances

[yonewt]

Homework Statement

A particle which moves with a constant acceleration in a straight line passes through the point O, A and B in that order. If the distances OA and AB are 17 m and 35 m respectively and the particle takes the same amount of time , 3 seconds to travel each distance then calculate

i)acceleration

ii) the time taken to travel 105 m from O

Homework Equations

s = ut + .5at^2

The Attempt at a Solution

i figured out the acceleration. the second part is giving me trouble

 

[haruspex]

What did you get for a? Did you also calculate u at O?

 

[yonewt]

no i didnt get u. i got a to be 2ms^-2

 

[haruspex]

Yes, that's right for a. If you now calculate u at O, can you see how to finish the question?

 

[yonewt]

how do i go about calculating u at O? can u explain to me?

 

[haruspex]

how do i go about calculating u at O? can u explain to me?

Well, how did you calculate a? The equation you quoted has a u in it.

 

[yonewt]

Well, how did you calculate a? The equation you quoted has a u in it.

yeah i do but i don't know how to go about finding u at O can you explain to me how?

 

[haruspex]

please post your working for how you calculated a.