5 Two racing cars \(A\) and \(B\) are at rest alongside each other at a point \(O\) on a straight horizontal test track. The mass of \(A\) is 1200 kg . The engine of \(A\) produces a constant driving force of 4500 N . When \(A\) arrives at a point \(P\) its speed is \(25 \mathrm {~ms} ^ { - 1 }\). The distance \(O P\) is \(d \mathrm {~m}\). The work done against the resistance force experienced by \(A\) between \(O\) and \(P\) is 75000 J .

1. Show that \(d = 100\).
   Car \(B\) starts off at the same instant as car \(A\). The two cars arrive at \(P\) simultaneously and with the same speed. The engine of \(B\) produces a driving force of 3200 N and the car experiences a constant resistance to motion of 1200 N .
2. Find the mass of \(B\).
3. Find the steady speed which \(B\) can maintain when its engine is working at the same rate as it is at \(P\).