1 m/s². A runner that change is speed from 6 m/s to 10 m/s has an aceleration of 1 m/s².
the key to solving this problem is using the kinematics equation
which means that the aceleration is related to a change of velocity in an interval of time.
We know that the runners runs at a initial velocity of 6 m/s, four seconds later, she is running at a speed of 10 m/s.
![a=(10(m)/(s)-6(m)/(s))/(4s) \\a=1(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/kv6j7ez8nkthk299gcckgkev3r1d4u14j5.png)