Answer: 2.45 seconds
Explanation: Acceleration a = -5, distance s = 15, time = ?.
Final velocity = v = 0.
We need to use the equations of motion under constant acceleration.
v^2 = u^2 + 2as where u is the initial velocity
0 = u^2 + 2*-5*15
u^2 = 150
so u = √150
Now we use v = u + at:
0 = √150 - 5t
t = √150/5
t = 2.45 seconds.
