Treadmill: Find the work output

A 60 kg subject walks at a speed of 3.5 mph at a 3.5% grade/incline for 15 min.

A 75 kg subject runs at a speed of 6.0 mph at a 0% grade/incline for 30 min.

power = 32.09 watt

work done = 28854 J

Explanation:

a) mass of subject = 60 kg speed = 3.5 mph = 5.63 kph = 1.564 m/s

grade = 3.5% time = 15 min

tan θ = 0.035

θ = 2°

power = F * v

= mg sin θ * v cos Φ

= 60 * 9.8 * sin2° * 1.564 * cos 180°

= - 32.09 watt

work done = power * time

= 28854 J

b) in this part work done is equal to zero.

because the angle between the motion of subject and the force acting is 90° hence cos 90° equals to zero so, work done equal to zero.