the idea is that when the object is at O, displacement=0
therefore, using the displacement formula which you should have found in part ii, make displacement (s) = 0
afterwards, find the value of t.
“since the value of t is ~6s for s=0, the particle must have been at O again around the ~6s”

alternatively, you sub t=6 into your displacement eqn. if the particle travels in the positive direction initially, make sure that displacement (s) when t=6 is negative (because only passing through O will give you a negative direction.)

but if you sub t=6 and you don’t get a negative (original and new displacements are both +ve or -ve, you cannot use this method because it does not prove that it passed through O)

hope these helps

Hi, would you be able to show to steps for solving s=0?

hi, my apologies. for this question you are unable to do that as there is no direct way to get to the answer when making s=0 as the variable t does not only belong to e. so sorry abt that