The object starts to move in a straight line with uniform acceleration from a static state, and the acceleration is 2m / s. The distance it passes in a certain 1s is 15m. Find (1) what is the velocity of the object at the beginning of 1s? (2) how long has the object moved before 1s? (3) how many distances has the object passed before 1s

Let it pass 15 meters in the second t to t + 1
（1/2)a(t+1)^2 - (1/2)at^2 = 15
Substituting a = 2, t = 7 (seconds)
Initial velocity in this second: V7 = at = 14 (M / s)
Distance passed one second ago: S7 = (1 / 2) at ^ 2 = 49 (m)

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