Question

The drag coefficient = 0.354
The mass of car = 1200 kg
rolling resistance = 180 N
Air density = 1.181 kg m^-3
Frontal area = 1.88 m^2

What is the deceleration at a speed of 82 km h^-1 when the car is taken up to high speed and then allowed to coast down on a level road.

Answer 1

Deceleration = (net backwards force) / mass
82 km/h = 22.78 m/s

Air drag force = (1/2)*(density)*(frontal area)*V^2
= (0.5)*(1.181)*(1.88)*(22.78)^2
= 576 N
Rolling resistance = 180 N

deceleration = (576+180)/1200 = 0.63 m/s^2