ANSWER:
(a) negative
(b) -120.3 N
STEP-BY-STEP EXPLANATION:
(a)
The net work done on the car is negative because its speed decreases from 19 m/s to 12 m/s
(b)
The acceleration is found from the equationof motion that:
[tex]v^2-u^2=2\cdot a\cdot s[/tex]Replacing and solving for a:
[tex]\begin{gathered} 12-19=2\cdot a\cdot32 \\ -7=64a \\ a=-\frac{7}{64}\frac{m}{s^2} \end{gathered}[/tex]Therefore, the force would be:
[tex]\begin{gathered} F=m\cdot a \\ F=1100\cdot-\frac{7}{64} \\ F=-120.3\text{ N} \end{gathered}[/tex]