Dynamics Question: Calculate Resistive Force on Car

[K.QMUL]

Homework Statement

Along a certain section of road a car (mass 1600kg) will coast in neutral at a constant speed of 72 km/h if there is no wind. Examination of a topological map shows that for this section of road the elevation decreases by 200m for each 6000m of road. What is the total resistive force (friction plus air resistance) that acts on the car when it is traveling at 72 km/h?

Homework Equations

P=FV, f=ma

The Attempt at a Solution

Please see the image attached

-Thanks for any help

 

[arildno]

Seems fine to me!