Problem 10.39 Part A Assume that a 1.20 kg ball is thrown solely by the action o

Question

Problem 10.39 Part A Assume that a 1.20 kg ball is thrown solely by the action of the forearm, which rotates about the elbow joint under the action of the triceps muscle, see the figure. (Figure 1) The ball is accelerated uniformly from rest to 8.9 m/s in 0.32 s, at which point it is released Calculate the angular acceleration of the arm. Assume that the forearm has a mass of 3.8 kg and rotates like a uniform rod about an axis at its end. Express your answer to two significant figures and include the appropriate units. Previous Answers Correct Part B Calculate the force required of the triceps muscle. Express your answer to two significant figures and include the appropriate units. F-1 Value Units tte Submit Figure 1 of 1 X Incorrect: Try Again; 4 attempts remaining Provide Feedback 31 cm Axis of rotation 2.5 cm (at elbow Triceps muscle

Explanation / Answer

givne

m = 1.2 kg

u = 0 m/s

v = 8.9 m/s

t = 0.32 s

hence

a. angular acceleration of the arm = a/0.31 m

a = (v - u)/t = 27.8125 m/s/s

alpah = 89.7177419 rad/s/s

b. force = F

then

F*0.025 = m*0.31^2*alpha

hence

F = 413.85 N

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