Question

The drag force, fd, imposed by the surrounding air on a vehicle moving with velocity v is given by fd = cdaρv 2/2 where cd is a constant called the drag coefficient, a is the projected frontal area of the vehicle, and ρ is the air density. an automobile is moving at v = 80 kilometers per hour with cd = 0.28, a = 2.3 m2, and ρ = 1.2 kg/m3.

Answer 1

Answer: 191 N

Explanation:

Given that,

Velocity v = 80 km/hr

Area $a = 2.3\ m^{2}$

Air density $\rho = 1.2\ kg/m^{3}$

Constant cd = 0.28

We know the drag force,

$F_{d} = cda\dfrac{1}{2}\rho v^{2}$

$F_{d} = 0.28\times 2.3\ m^{2}\times\dfrac{1}{2}\times1.2\ kg/m^{3} \times (\dfrac{800}{36}\ m/s)^{2}$

$F_{d} = 190.8 N$

$F_{d} = 191 N$

Hence, the drag force is 191 N.