Answer
a. 393N
b. Thicker strings.
Work Step by Step
a. Set the tensile strength of nylon (Table 9-2) equal to the applied stress on the string.
tensile strength = $\frac{F_{max}}{A}$
$$F_{max}=(500\times 10^6 N/m^2)( \pi (0.0005 m)^2)= 393 N $$
b. To prevent breakage, use thicker strings with greater cross-sectional area. When the ball hits the strings, the tension increases, which may break the strings.
