Answer:
a) Drag force = 5.67 N
b) Fraction of (drag force/weight) = 0.00964 = 0.964% (just less than 1%)
Step-by-step explanation:
Drag force is given by the expression
Drag force = CρAv²/2
C = Drag coefficient of air for an average human moving through air = 1.0
ρ = density of air = 1.2 kg/m³
A = Cross sectional Area of runner facing the air = 0.72 m²
v = velocity of the runner = (5km/23min) = (5000/23×60) = 3.623 m/s
Drag force = 1(1.2)(0.72)(3.623²)/2
Drag force = 5.67 N
b) Runner's weight = mg = 60×9.8 = 588 N
Fraction of (drag force/weight) = (5.67/588) = 0.00964 = 0.964% (just less than 1%)
