Final answer:
The propulsive force on the car is 1500 N, as it equals the sum of the friction and air resistance forces. The car takes approximately 23.52 seconds to travel 490 meters, calculated by dividing the distance by the car's speed in m/s.
Step-by-step explanation:
To determine the propulsive force on the car, we must understand that the car is traveling at a constant speed, which implies that the net force acting on the car is zero. Therefore, the sum of all forward forces must be equal to the sum of all the backward forces. Since the backward forces are a friction force and air resistance, the propulsive force provided by the car's engine must be equal to the sum of these two resistive forces.
The total resistive force can be calculated by adding the friction force (880 N) and the air resistance force (620 N), giving a total resistive force of 1500 N. Thus, the propulsive forward force must also be 1500 N to maintain a constant velocity.
For part b), to find the time it takes the car to travel 490 m, we start by converting the speed from km/h to m/s: 75.0 km/h is equivalent to 75.0 * (1000 m/1 km) * (1 h/3600 s) = 20.83 m/s. Now, using the formula distance = speed x time, we can solve for the time: time = distance/speed. So, time = 490 m / 20.83 m/s, which equals approximately 23.52 seconds.