(a) To find the net force on the blood in the artery, we can use the following formula:
Net force = pressure drop * cross-sectional area
The pressure drop is given as 100 Pa and the radius of the artery is 10 mm, which is equivalent to 0.01 m. The cross-sectional area can be calculated using the formula for the area of a circle:
A = πr^2
A = π(0.01)^2
A = π*0.0001
A = 0.000314 m^2
Now we can calculate the net force:
Net force = 100 * 0.000314
Net force = 0.0314 N
Therefore, the net force on the blood in this section of artery is 0.0314 N.
(b) To find the power expended maintaining the flow, we can use the formula:
Power = Net force * average velocity
The average velocity of the blood is given as 15 mm/s, which is equivalent to 0.015 m/s. Now we can calculate the power:
Power = 0.0314 * 0.015
Power = 0.000471 W
Therefore, the power expended maintaining the flow is 0.000471 W.