Final answer:
The question involves the concept of Hooke's law and the calculation of the force constant of a spring. When Bob and Carlos pull on the spring with equal forces, the additional force causes further stretch.
Step-by-step explanation:
The question involves the concept of Hooke's law, which states that the force applied to stretch or compress a spring is directly proportional to the displacement.
In this case, when Bob pulls on one end of the spring with a 200 N force, the spring stretches by 20 cm. This means that the force constant of the spring can be calculated as:
k = F/x
k = 200 N / 0.20 m = 1000 N/m
When Carlos also pulls with a 200 N force, the total force exerted on the spring is 400 N. Since the displacement is the same, the spring will stretch a further 20 cm due to the additional force.