The length of the spring when two people pull in opposite directions on the ends of the spring with 140 N of force can be calculated as follows.The weight and spring are taken down, which means that there is no force acting on the spring other than the force applied by the two people. So, the force acting on the spring is 2 × 140 = 280 N.Assuming the spring is extended by x meters in this situation, then the force applied on the spring is proportional to the extension of the spring. Therefore, we can say that:F=kxwhere F is the force applied, k is the spring constant, and x is the extension of the spring.Since we know that F = 280 N, we can write:F = kx280 = kxSince the length of the spring is not given, we can't calculate the spring constant. Therefore, we need more information to solve the problem.