Motion on Incline Problem: Find 1st Mark in 2.5s

[Cole07]

problem: A ball is allowed to roll from rest down an inclined plane, and the distances are marked every 2.5s. if the second mark is made 1.5m from the starting point, where is the first mark?

where is the fourth mark?

well i made a velocity vs. t chart and the velocity of it is 0.6 then ifound the velocity of ech number on my graph but iwas told my answer was wrong. can you help me please.

 

[blackwizard]

well the ball is going to accelerate as it rolls down the plane. it sounds like ur assumin the velocity stays the same