Halliday, Resnick & Walker — Potential Energy and Conservation of Energy: Problem 15

15 In Fig. 8-24, a runaway truck with failed brakes is moving downgrade at 130 km/h just before the driver steers the truck up a frictionless emergency escape ramp with an inclination of \(\theta = 15^\circ\). The truck's mass is \(1.2 \times 10^4 \text{ kg}\). (a) What minimum length \(L\) must the ramp have if the truck is to stop (momentarily) along it? (Assume the truck is a particle, and justify that assumption.) Does the minimum length \(L\) increase, decrease, or remain the same if (b) the truck's mass is decreased and (c) its speed is decreased?