ANSWER
[tex]16,233.112\text{ }J[/tex]EXPLANATION
b) We want to find the change in gravitational potential energy of the lorry.
The change in gravitational potential energy is given by:
[tex]\Delta PE=mg\Delta h[/tex]where m = mass of the lorry
g = acceleration due to gravity
Δh = change in height
Let us make a sketch of the problem:
To find the change in height, we have to apply the trigonometric ratios:
[tex]\sin15=\frac{\Delta h}{1600}[/tex]Therefore, the change in height is:
[tex]\begin{gathered} \Delta h=1500*\sin15 \\ \\ \Delta h=414.11\text{ m} \end{gathered}[/tex]Therefore, the change in gravitational potential energy of the lorry is:
[tex]\begin{gathered} \Delta PE=4000*9.8*414.11 \\ \\ \Delta PE=16,233.112J \end{gathered}[/tex]That is the answer.
