A truck of mass 750 kg is moving with constant speed \(v \mathrm {~m} \mathrm {~s} ^ { - 1 }\) down a straight road inclined at an angle \(\theta\) to the horizontal, where \(\sin \theta = \frac { 3 } { 49 }\). The resistance to motion of the truck is modelled as a constant force of magnitude 1200 N . The engine of the truck is working at a constant rate of 9 kW .
Find the value of \(v\).
On another occasion the truck is moving up the same straight road. The resistance to motion of the truck from non-gravitational forces is modelled as a constant force of magnitude 1200 N . The engine of the truck is working at a constant rate of 9 kW .
Find the acceleration of the truck at the instant when it is moving with speed \(4.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).