Homework

1. Determine the maximum grade an empty tractor-trailer with a mass of 10000 kg can climb at a sustained speed of 75 km/h.

The frontal area (A) of the truck is 10 m², the drag coefficient = 1.00 and the available power is 280 kW, ρ=1.2 kg*m⁻³, g = 9.81 m*sec⁻²

2. What is the maximum grade a bicycle can climb at a sustained speed of 12 km/h assuming the following:

• Rho = density of air (1.20 kg*m⁻³)
• g = 9.81 m*sec⁻²
• Mass (with bicyclist) = 100 kg
• Nominal Power = 1 kW
• Frontal Area (A) = 1 m²
• Drag Coefficient = 0.5
• Available power = 100 percent of nominal power
• Fr = 0.020 W

3. Bicyclists get tired. Assume the bicyclist slowly loses power (and thus velocity) going up the hill of the grade you just determined in question 2 above. If available power drops continuously from 100% to 0% over the course of the hour, to the nearest kilometer, how far does the bicyclist travel? (Use appropriate approximations.)