Answer:
[tex]\boxed {\boxed {\sf a= \frac {2}{5} \ or \ 0.4 \ m/s^2}}[/tex]
Explanation:
Acceleration is found by dividing the change in velocity by the time. The formula is:
[tex]a= \frac {v_f-v_i}{t}[/tex]
where [tex]v_f[/tex] is the final velocity, [tex]v_i[/tex] is the initial or starting velocity, and [tex]t[/tex] is the time.
Her velocity changes from 2 meters per second to 4 meters per second in the 5 seconds. Therefore:
[tex]v_f= 4 \ m/s \\v_i= 2 \ m/s \\t=5 \ s[/tex]
Substitute the values into the formula.
[tex]a= \frac { 4 \ m/s- 2 \ m/s}{5 \ s}[/tex]
Solve the numerator and subtract.
[tex]a= \frac { 2 \ m/s}{5 \ s}[/tex]
Divide.
[tex]a= \frac{2}{5} \ m/s/s= \frac{2}{5} \ m/s^2[/tex]
This can also be written as a decimal.
[tex]a=0.4 \ m/s^2[/tex]
Her average acceleration during the last 5 seconds of the race is 2/5 or 0.4 meters per square second.
