10. You pull on a spring, which obeys Hooke's law, in two steps. In step 1, you extend it by distance IN. In step 2, you further extend it by the same distance z,. Choose the answer that correctly compares the elastic potential energy of the spring after the first step (U₁1) with that after the second step (U₁2). a. U₁2= 2U1 because the force exerted on the spring at the end of step 2 is two times larger than at the end of step 1. b. U₁2 2U₁1 because the extension of the spring at the end of step 2 is two times larger than the extension of the spring at the end of step 1. c. U₁2> 2U₁1 because the more the spring is stretched, the larger the force that is needed to extend the spring for a unit distance. d. U₁2> 2U1 because the average force exerted on the spring in step 2 is more than two times larger than the average force exerted on the spring in step 1.

10. You pull on a spring, which obeys Hooke's law, in two steps. In step 1, you extend it by distance IN. In step 2, you further extend it by the same distance z,. Choose the answer that correctly compares the elastic potential energy of the spring after the first step (U₁1) with that after the second step (U₁2). a. U₁2= 2U1 because the force exerted on the spring at the end of step 2 is two times larger than at the end of step 1. b. U₁2 2U₁1 because the extension of the spring at the end of step 2 is two times larger than the extension of the spring at the end of step 1. c. U₁2> 2U₁1 because the more the spring is stretched, the larger the force that is needed to extend the spring for a unit distance. d. U₁2> 2U1 because the average force exerted on the spring in step 2 is more than two times larger than the average force exerted on the spring in step 1.