While a person is walking, his arms swing through approximately a 45.0 angle in

Question

While a person is walking, his arms swing through approximately a 45.0 angle in 0.440 s . As a reasonable approximation, we can assume that the arm moves with constant speed during each swing. A typical arm is 70.0 cm long, measured from the shoulder joint.

a) What is the acceleration of a 1.00 gram drop of blood in the fingertips at the bottom of the swing? b)Find the force that the blood vessel must exert on the drop of blood in part (a).

c)What force would the blood vessel exert if the arm were not swinging?

Explanation / Answer

a) 45 degrees in 0.44 sec

angular speed w = (45 x pi /180 )rad / 0.44sec = 1.785 rad/s

there will centripetal acc. towrads shoulder.

aC = w^2 R

aC = 1.785^2 x 0.70 = 2.23 m/s^2

b) Balancing forces in blood in vertical,

F - mg = maC

F = 1 x 10^-3 ( 9.81 + 2.23) = 12.04 x 10^-3 N Or 12.04 mN

c) then F = mg = 1 x 10^-3 x 9.81 = 9.81 x 10^-3 N Or 9.81 mN

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