Integrated Concepts Suppose we replace the 4.0-kg book in Exercise 9.31 of the biceps muscle with an elastic exercise rope that obeys Hooke’s Law. Assume its force constant k = 600 N/m . (a) How much is the rope stretched (past equilibrium) to provide the sam? e force ?FB as in this example? Assume the rope is held in the hand at the same location as the book. (b) What force is on the biceps muscle if the exercise rope is pulled straight up so that the forearm makes an angle of 25º with the horizontal? Assume the biceps muscle is still perpendicular to the forearm. Reference Exercise 9.31: We analyzed the biceps muscle example with the angle between forearm and upper arm set at 90º. Using the same numbers as in Example 9.4, find the force exerted by the biceps muscle when the angle is 120º and the forearm is in a downward position. 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 36PE Step-by-step solution Step 1 of 2 (a) From below mention Hook’s law; calculate how much distance rope distance rope is the stretched, Here, is the biceps force and is forceconstant and x is rope distance. Since Biceps force is equal to the weight of the book. Therefore, Here, m is the m ass of book and g is acceleration due to gravity. Hence substitute , Substitute 4.0 kg for m , 9.8 m/s2 for g and 600 N/m solve for x, Hence, rope is stretched is .