Introduction and Vehicle Motion

Part 1: Introduction

1. What do the following acronyms stand for:

a. DOT:

b. FHWA:

c. FRA:

d. FAA:

e. FTA:

2. The Highway Trust Fund is used to finance road construction in the US through a federal tax on gasoline. Explain how financing transportation infrastructure through the gas tax conflicts with environmental objectives. (Consider the taxes paid by a hybrid car like a Toyota Prius vs. a conventional vehicle).

3. Briefly define the term Megaregion.

4. Briefly define the term "Exit Ramp Economy"

Part 2: Vehicle Motion (Kinematics and Dynamics)

1. The acceleration of a vehicle takes the form  a= 8.0 e^-0.01??  where ?? is the vehicle speed in ft/sec. At time ?? = 0 the vehicle is traveling at 40 ft/sec at location ???? = 0.

a. Determine the time at which the vehicle attains the speed of 75 ft/sec.

b. Determine the distance traveled by the vehicle when accelerated to a speed of 75 ft/sec.

c. Determine the acceleration of the vehicle after 10 seconds.

2. The acceleration of a vehicle takes the following forms: a = 2.8 - 0.05v where v is the vehicle speed in ft./sec. At time 0 the vehicle is traveling at 30ft/sec at location x=0.

a. Determine the time at which the vehicle attains the speed of 50 ft/sec.

b. Determine the distance traveled by the vehicle when accelerated to a speed of 50 ft/sec

c. Determine the acceleration of the vehicle after 5 seconds.

3. A 2500-lb car is designed with a 120" wheelbase. The center of gravity is located 22" above the ground. The coefficient of road adhesion is 0.6. How far back from the front axle would center of gravity have to be to ensure that the maximum tractive effort developed for front-and rear-wheel drive options is equal?

4. A vehicle manufacturer is considering an engine for a new sedan. C_D = 0.34, A_f = 22 ft². The car is being designed to achieve a top speed of 100 mph on a paved surface at sea level (ρ = 0.002378 slugs/ft³). The car currently weighs 2500 lb., but the designers initially selected an underpowered engine because they did not account for aerodynamic and rolling resistances. If 2 lb. of additional vehicle weight is added for each unit of horsepower needed to overcome the neglected resistance, what will be the final weight of the car if it is to achieve the 100 mph top speed? (Hint: If you add 2x lb. of additional weight, x hp of additional power is required. You equate that to the resistance you are trying to overcome)

5. A rear-wheel drive car weighs 2600 lb. and has an 84 inch wheelbase, center of gravity 20 inches above the roadway surface, and 30 inches behind the front axle; drive train efficiency of 85%, 14-inch radius wheels, and an overall gear reduction of 7 to 1. The car's torque/engine speed curve is given by M_e= 6ne-0.045n_e². If the car is on a paved, level roadway surface with a coefficient of adhesion of 0.75, determine its maximum acceleration from rest.