59.00 PM 2-00:00 AM-Due Date: 11/3/201 he woman doing push-ups in the figure. Sh

Question

59.00 PM 2-00:00 AM-Due Date: 11/3/201 he woman doing push-ups in the figure. She has a (14%) Problem 6: Consider t mass of 49.2 kg, and the distance from her feet to her center of mass is 0.99 m, while the distance from her feet to her hands is 1.65m CG moves up at a constant speed. Grade Summary tus Potential 100 sin Submisions Attempts remaining 3 (4% per attempt detailed vien Hints: -dedaetion per hint Hmts remaining J 25% Part (b) The triceps muscle at the back of her upper arm has an effective lever arm of ISS em, and she exerts force on the floor at a horizontal distance of IS em from the elbow joint Calculate the magnitude of the force in nevwtons for each triceps muscle. 2596 Part (c) How much work in joules does she do if ber center of mass rises 6.15 m?

Explanation / Answer

mass m = 49.2 kg

a = 0.99 m

b = 1.65 m

a. from the figure

using force balance

w = Fp + Fr

49.2*9.81 = Fp + Fr

from torque balance about the foot

w*a = Fr*b

49.2*9.81*0.99 = Fr*1.65

Fr = 289.5912 N

hence force by each hand = Fr/2 = 144.7956 N

b. lever arm, l = 1.95 cm

d = 15 cm

hence force per tricep muscle = F

F*1.95 = 144.7956*15

F = 1113.8123 N

c. d = 0.15 m

work done = mgh = 49.2*9.81*0.15 = 72.3978 J

d. for 25 pushups pre minute

power = 72.3978*25/60 = 30.16575 W

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