Answer:
The runner's acceleration was [tex]1\ m/s^2[/tex]
Explanation:
Constant Acceleration Motion
It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.
Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:
[tex]v_f=v_o+at[/tex]
Solving for a:
[tex]\displaystyle a=\frac{v_f-v_o}{t}[/tex]
The runner speeds up from vo=5 m/s to vf=9 m/s in t=4 seconds, thus:
[tex]\displaystyle a=\frac{9-5}{4}[/tex]
[tex]\displaystyle a=\frac{4}{4}=1[/tex]
The runner's acceleration was [tex]1\ m/s^2[/tex]
