Question

Running on a treadmill is slightly easier than running outside because there is no drag force to work against. Suppose a 60 kg runner completes a 5.0 km race in 17 minutes. Determine the drag force on the runner during the race. Suppose that the cross section area of the runner is 0.72 m2.

Answer 1

Drag force = 2.20N.

Step-by-step explanation:

Given data:

Weight of the runner = 60kg

Distance completed by the runner = 5km

Time spent to cover the distance = 17 minutes.

Cross sectional area = 0.72m^2.

Density of air = 1.2kg/m^3.

Solution:

V = d/t

Where d = 5km

t = 17 mins

V = (5*103)/(17*60)

= 5.1m/s

The drag force experienced by a person

Fd = 1/2 p C A v2

= 1/2 * 1.2 * 1 * 0.72 * 5.1

= 2.20N

f = f = Fd / m g

f = 2.20 / (60 * 9.8)

= 3.74*10^-3