Final answer:
The potential energy stored in Spring B is twice as great as that stored in Spring A, assuming they are stretched the same distance, because Spring B's spring constant is twice that of Spring A.
Step-by-step explanation:
The question involves comparing the potential energy stored in two springs with different spring constants stretched the same distance. The potential energy stored in a spring is given by the expression U = 1/2 k x^2, where U is the potential energy, k is the spring constant, and x is the displacement from the spring's rest length.
Spring A has a spring constant of 140 N/m, and Spring B has a spring constant of 280 N/m. With both springs stretched the same distance, the potential energy stored in Spring B would be twice as great as that stored in Spring A because the spring constant for Spring B is twice that of Spring A. Since the potential energy is directly proportional to the spring constant, doubling the spring constant (assuming the displacement is the same) doubles the potential energy stored.