**1. The engine of an automobile requires 45hp to maintain a constant speed of 80 km/h**

a. What is the resistive force against the automobile?

The answer given here is 1510.80N but don't know how they get it.

b. If the resistive force is proportional to the velocity, what must the engine power be to drive at constant speed of 60km/h?

a. What is the resistive force against the automobile?

The answer given here is 1510.80N but don't know how they get it.

b. If the resistive force is proportional to the velocity, what must the engine power be to drive at constant speed of 60km/h?

2.

**I have no idea**

**3. at letter a. i tried to convert 45hp to 33556.49J/s and converted also 80km/h to 22.22 m/s, after that I divided 33556.49J/s to 22.22 m/s and got an answer 1510.19 N. The letter b. I have no idea**

Last edited: