Standard +0.3 This is a straightforward mechanics problem requiring application of the work-energy principle. Students must calculate work done against gravity (mgh), work against resistance (Fd), and change in kinetic energy, then divide total work by time to find power. All steps are standard and clearly signposted, making it slightly easier than average.
8 A car of mass 1 tonne reaches the foot of an incline travelling at \(30 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). It reaches the top of the incline 50 seconds later travelling at \(10 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). The length of the incline is 1200 m and the angle made with the horizontal is \(\sin ^ { - 1 } \left( \frac { 1 } { 8 } \right)\). The constant resistance to motion is 400 N . Find the average power developed by the engine of the car.
8 A car of mass 1 tonne reaches the foot of an incline travelling at $30 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. It reaches the top of the incline 50 seconds later travelling at $10 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. The length of the incline is 1200 m and the angle made with the horizontal is $\sin ^ { - 1 } \left( \frac { 1 } { 8 } \right)$. The constant resistance to motion is 400 N . Find the average power developed by the engine of the car.
\hfill \mbox{\textit{Pre-U Pre-U 9795/2 2013 Q8}}