# Homework Help: Constant acceleration in a straight line with variable distances

1. May 8, 2013

### yonewt

1. The problem statement, all variables and given/known data

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

2. Relevant equations
s = ut + .5at^2

3. The attempt at a solution

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

2. May 8, 2013

### haruspex

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

3. May 8, 2013

### yonewt

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

4. May 8, 2013

### haruspex

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

5. May 9, 2013

### yonewt

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

6. May 9, 2013

### haruspex

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

7. May 9, 2013

### yonewt

yeah i do but i dont know how to go about finding u at O can you explain to me how?

8. May 9, 2013