ANSWER:
180 J
STEP-BY-STEP EXPLANATION:
To know the work required we must calculate the work at 7 m/s and at 2 m/s, the difference would be the work required.
The work done is the same as the amount of energy increase. The formula for kinetic energy is:
[tex]\frac{1}{2}m\cdot v^2[/tex]We calculate in each case:
[tex]\begin{gathered} \frac{1}{2}\cdot8\cdot7^2=196\text{ J} \\ \frac{1}{2}\cdot8\cdot2^2=16\text{ J} \end{gathered}[/tex]The difference between these is the amount of work done:
[tex]W=196-16=180\text{ J}[/tex]The work required is 180 J
