# Worksheet: Elastic Potential Energy

In this worksheet, we will practice calculating the elastic potential energy stored in springs that are not at their equilibrium length.

**Q1: **

The keys on a computer keyboard contain small springs that compress by 4.8 mm when a key is pressed. On a particular day, 12โ500 keystrokes are made on the keyboard. The springs in the keys each have a constant of 2.5 N/m. How much energy was supplied to make all the keystrokes performed that day?

**Q2: **

A spring with a constant of 16 N/m has 98 J of energy stored in it when it is extended. How far is the spring extended?

**Q3: **

A spring has 50 J of energy stored in it when it is extended by 2.5 m. What is the springโs constant?

**Q4: **

A spring with a constant of 80 N/m is extended by 1.5 m. How much energy is stored in the extended spring?

**Q5: **

The quantity is a springโs elastic potential energy when the spring is extended or compressed. Which of the following formulas correctly shows the relationship between , the constant of the spring , and the change in the length of the spring from its equilibrium length?

- A
- B
- C
- D
- E

**Q6: **

A man with a weight of 900 N lies down on a spring-loaded mattress. The combined force constant of all the springs in the mattress is 18,000 N/m. How much elastic potential energy is stored in the bedโs springs?

**Q7: **

A spring with a force constant of 500 N/m is extended from its equilibrium length by 12 cm. From its extended length, the spring is shortened by 7 cm. The spring is then shortened from this length by 15 cm.

How much does the springโs elastic potential energy change during the first time it is shortened?

How much does the springโs elastic potential energy change during the second time it is shortened?

**Q8: **

The force used to stretch a spring is shown in the graph. How much work is required to extend the spring by 0.6 m?