that the force in the elbow joint in Example 9.4 is 407 N, as stated in the text. Example 9.4: Muscles Exert Bigger Forces Than You Might Think Calculate the force the biceps muscle must exert to hold the forearm and its load as shown in ?Figure 9.27?, and compare this force with the weight of the forearm plus its load. You may take the data in the figure to be accurate to three significant figures.

Solution 26PE Step-by-step solution Step 1 of 2 Refer to the figure 9.27(a) provided in the text book. Consider the force of the biceps muscle must exert to hold the forearm and its load as shown in figure. Torque about pivot point is zero , Here, is weight of forearm, is distance between force exerted by biceps and force at elbow, is distance between force exerted by elbow and weight of forearms, is load, is distance between load and force at elbow joint and is force at elbow joint. Calculate weight of forearm, Here, is mass of forearm and g is acceleration due to gravity. Substitute 2.5 kg for m and 9.8 m/s2 for g calculate weight of forearm, Calculate load, Substitute 4.0 kg for m and 9.8 m/s2 for g calculate load,