A man is doing push-ups, as shown in the figure below. He has a mass of 71.5 kg
ID: 1284038 • Letter: A
Question
A man is doing push-ups, as shown in the figure below. He has a mass of 71.5 kg and his center of gravity is located at a horizontal distance of d1 = 0.774 m from his palms and d2 = 1.14 m from his feet. (A)Calculate the forces exerted by the floor on his palms. (b) Now calculate the forces exerted by the floor on his feet.
A man is doing push-ups, as shown in the figure below. He has a mass of 71.5 kg and his center of gravity is located at a horizontal distance of d1 = 0.774 m from his palms and d2 = 1.14 m from his feet. (A)Calculate the forces exerted by the floor on his palms. (b) Now calculate the forces exerted by the floor on his feet.Explanation / Answer
Man mass is 71.5 kg so gravitational force exerted by him be 71.5 X 9.8 m/s2 =700.7N
Let H denote hand and F denote foot
2H------------0.774 m-------------700.7N---------1.14 m---------2F
2F + 2H = 700.7 N
Take moments about 2F:
2H x (0.774 + 1.14) m = 700.7 N x 1.14 m = 798.79 Nm
2H = 798.79 N/1.914 = 417.34 N
H = 417.34/2 = 208.67 N
2F = 700.7 N - 417.3 N = 283.4
F = 283.7/2 = 141.85 N
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