Question

How much elastic potential energy is stored in a bungee cord with a spring constant of 10.0 N/m when the cord is stretched 2.00 m?
A. 10.0 J
B. 20.0 J
C. 40.0 J
D. 200 J

Answer 1

Elastic potential energy stored in bungee cord is 20.0 J.

Answer: Option B

Explanation:

The elastic potential energy is a form of potential energy stored in elastic materials. Generally potential energy is the energy of any object when it is at rest. But in materials possessing elastic properties, they store these potential energy in the form of elastic potential energy and it is used when the elastic materials undergoes elastic deformation.

For example, if we consider a spring, the elastic potential energy of the spring will be zero, when it is not deformed elastically i.e., when the spring is not stretched or compressed. But the same spring will be exhibiting elastic potential energy when the spring is stretched or compressed. So, the formula for elastic potential energy is

      $\text { Elastic potential energy }=\frac{1}{2} \times \text { spring constant } \times\left(\frac{\text {stretching}}{\text {compressing distance}}\right)^{2}$

In this case, as the spring constant of cord is given as 10 N/m and the stretching distance of the cord is given as 2 m, so the elastic potential energy stored in the cord will be

       $\text { Elastic potential energy }=\frac{1}{2} \times 10 \times(2)^{2}=\frac{1}{2} \times 10 \times 4 = 20 J$

Answer 2

the correct answer is B. 20.0 J