GRAPHICAL \& INTEGRAL METHODS
6
A force of 5.0 N was applied to a particle to move it 4 meters to the right. The applied force decreases to zero in the next 2 meters. Calculate the work done by the force on the particle.
SOLUTION (GRAPHICAL)
The net work done by this force
\[
\begin{aligned}
W_{\text {Ato } \mathrm{C}}= & W_{\mathrm{Ato} \mathrm{B}}+W_{\mathrm{B} \text { to } \mathrm{C}} \\
& W_{\text {A to B }}=(5.0 \mathrm{~N})(4.0 \mathrm{~m})=20 \mathrm{~J} \\
& W_{\mathrm{B} \text { to } \mathrm{C}}=\frac{1}{2}(5.0 \mathrm{~N})(2.0 \mathrm{~m})=5.0 \mathrm{~J} \\
= & 20 \mathrm{~J}+5.0 \mathrm{~J}=25 \mathrm{~J}
\end{aligned}
\]