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.

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation: