To maintain a constant speed, the force provided by a car's engine must equal the drag force plus the force of friction of the road (the rolling resistance). what are the drag forces at 50 km/h and 80 km/h for a toyota camry? (drag area is 0.67 m2.)

Given:

A = 0.67 m², the area perpendicular to the direction of motion

v = 50 km/h and 80 km/h, traveling speeds

The drag force is

F = (1/2) CρAv²

where

C = 0.4, the drag coefficient (a low number for efficiently designed Camry)

ρ = 1.225 kg/m³, density of air

Note that 1 km/h ≈ 0.2778 m/s.

Therefore,

50 km/h = 13.89 m/s

80 km/h = 22.224 m/s

At 50 km/h, the drag force is

F₅₀ = 0.5*0.4 * (1.225 kg/m³) * (0.67 m²) * (13.89 m/s) ² = 31.67 N

At 80 km/h, the drag force is

F₈₀ = 0.5*0.4*1.225*0.67*22.224² = 81.075 N

Answers:

31.7 N at 50 km/h

81.1 N at 80 km/h