18 A rescue van is towing a broken-down car by using a tow bar.
The van and the car are moving with a constant acceleration of \(0.6 \mathrm {~ms} ^ { - 2 }\) along a straight horizontal road as shown in the diagram below.
\includegraphics[max width=\textwidth, alt={}, center]{9cd7f38d-a2a1-4fd3-9ed9-cb389e8ee3b6-22_77_163_511_991}
The van has a total mass of 2780 kg
The car has a total mass of 1620 kg
The van experiences a driving force of \(D\) newtons.
The van experiences a total resistance force of \(R\) newtons.
The car experiences a total resistance force of \(0.6 R\) newtons.
18
- The tension in the tow bar, \(T\) newtons, may be modelled by
$$T = k D - 18$$
where \(k\) is a constant.
Find \(k\)
18 - State one assumption that must be made in answering part (a).