Answers to Practice Questions

1.Describe the relationship between the spring constant and the elastic potential energy.

Relationship is directly proportional, so as the spring constant increases, so does the elastic potential energy. This means that as spring constant increases, so does elastic potential energy.

2.  A steel spring has a spring constant of  15N/m and when compressed its length decreases by 0.4m Calculate the elastic potential energy stored in the spring when it is compressed.

E_e = 1/2 x k x e²

E_e = 1/2 x 15 x 0.4²

E_e = 1/2 x 15 x 0.16

E_e = 1.2J

3. A resistance band has a spring constant of 30N/m. During an exercise its length is increased from 0.7m to 1.1m. Calculate the elastic potential energy stored in the resistance band.

Extension,e = 1.1m-0.7m = 0.4m

E_e = 1/2 x k x e²

E_e = 1/2 x 30 x 0.4²

E_e = 1/2 x 30 x 0.16

E_e = 2.4J

4. A catapult has 100kJ of elastic potential energy stored and its spring constant is 4000N/m. Calculate the extension that the catapult is experiencing.

100kJ = 100,000J