Answer:
4.12 seconds
Explanation:
From the kinetic equation
where s is the displacement, u is initial velocity, t is time of travel and a is acceleration.
Since the object is initially at rest, the initial velocity is zero hence the equation can be re-written as
and making t the subject of the formula

Substituting s for 85 m and a for 10 m/s2

Therefore, time is approximately 4.12 seconds