Answer:
2.0 m/s/s
Explanation:
The acceleration of an object is the rate of change of velocity of the object.
Mathematically, it is given by:
where
u is the initial velocity
v is the final velocity
t is the time taken for the velocity to change from u to v
Acceleration is a vector, so it has both a magnitude and a direction.
For the runner in this problem, we have:
u = 0 is the initial velocity (he starts from rest)
v = 8.0 m/s is the final velocity
t = 4.0 s is the time taken
Substituting, we find