Chapter 9, Problem 32P

To determine

Magnitude of force $F_m$ must the extensor muscle in the upper arm exert onthe lower arm

Answer to Problem 32P

Solution:

Magnitude of force $F_m$ is $\text{967}\text{N}$

Explanation of Solution

Given:

Mass of the shot put, $M_1=7.3\text{ kg}$

Mass of lower arm, $M_2=2.3\text{kg}$

Formula used:

Algebraic Sum of all the moments is zero

  ${\displaystyle \sum \tau =0}$

Calculation:

  $\text{Taking sum of all the moments about joint}$

  $\begin{array}{l}{\displaystyle \sum \tau }=0\\ F_m(0.025)-2.3(9.8)(0.12)-(7.3)(9.8)(0.30)=0\\ 0.025F_m=24.17\\ F_m=967\text{N}\end{array}$

Conclusion:

Thus, the force exerted by the extensor muscle is $\text{967}\text{N}$ .