he sign below is often seen on steep descents (Figure 1). It requires the driver to use the engine to retard the descent. Let's see why. A truck with a mass of 30 tonnes is travelling at the top of a straight descent with constant slope (Figure 1). Over a distance travelled L = 4.0 km the altitude of the road decreases by h = 468 m. This is a fairly steep slope. The true 0 drum brakes, which we'll treat as identical, each with a mass of 31 kg made from steel. TRUCKS & BUSES h MUST USE L LOW GEAR Diagram not to sca igure 1: Diagrammatic representation of a truck driving down a slope. The diagram shows a right-angled triangle. The vertical side is on the left with a height h and the truck is on the hypotenuse with a length L. The sign next to the diagram reads "Trucks and buses must use low gear". Part 1) What is the volume of each of the drum brakes at 0 °C? m Part 2) Suppose that the truck descends the slope at a constant speed of 28 km/h. Calculate the work done by gravity acting on the truck as it descends down this section of road.

he sign below is often seen on steep descents (Figure 1). It requires the driver to use the engine to retard the descent. Let's see why. A truck with a mass of 30 tonnes is travelling at the top of a straight descent with constant slope (Figure 1). Over a distance travelled L = 4.0 km the altitude of the road decreases by h = 468 m. This is a fairly steep slope. The true 0 drum brakes, which we'll treat as identical, each with a mass of 31 kg made from steel. TRUCKS & BUSES h MUST USE L LOW GEAR Diagram not to sca igure 1: Diagrammatic representation of a truck driving down a slope. The diagram shows a right-angled triangle. The vertical side is on the left with a height h and the truck is on the hypotenuse with a length L. The sign next to the diagram reads "Trucks and buses must use low gear". Part 1) What is the volume of each of the drum brakes at 0 °C? m Part 2) Suppose that the truck descends the slope at a constant speed of 28 km/h. Calculate the work done by gravity acting on the truck as it descends down this section of road.