A man holds a 170-N ball in his hand, with the forearm horizontal (see the figur

Question

A man holds a 170-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 23.7 N and has a center of gravity as indicated. Find (a) the magnitude of and the (b) magnitude and (c) direction (as a positive angle counterclockwise from horizontal) of the force applied by the upper arm bone to the forearm at the elbow

Explanation / Answer

a)

Equating torques about the elbow,

M*0.051 = 23.7*(0.051+0.089) + 170*(0.33)

So, M = 1165.1 N <-------answer

b)

Equating forces in vertical,

Fy + M = 23.7+170 <---- Fy = vertical force by upper arm bone

So, Fy = 23.7+170 - 1165.1 = -971.4 N <----- directed downwards

So, magnitude = 971.4 N

dircetion = 270 deg

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.