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→Key Stage 4
x = The [[Extension (Physics)|extension]] of the [[object]].
===Calculating Spring Constant===
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A bow with a spring constant of 400N/m is stretched 0.5m with a force of 200N. Calculate the elastic potential store of the bow.
| style="height:20px; width:200px; text-align:center;" |A bungee cord with a spring constant of 45N/m stretches by 30m. Calculate the elastic potential store of the cord.
Give your answer correct to 2 [[Significant Figures|significant figures]].
| style="height:20px; width:200px; text-align:center;" |A slinky spring of length 0.1m and spring constant 0.80N/m is stretched to a length of 9.1m. Calculate the elastic potential store of the slinky.
Give your answer correct to 2 [[Significant Figures|significant figures]].
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
k = 400N/m
x = 0.5m
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
k = 45N/m
x = 30m
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
k = 0.8N/m
Original Length = 0.1m
Final Length = 9.1m
'''Find the [[Extension (Physics)|extension]].'''
x = Final Length - Original Length = 9.1 - 0.1 = 9.0m
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and solve.'''
<math>E_e = \frac{1}{2} k x^2</math>
<math>E_e = \frac{1}{2} \times 400 \times 0.5^2</math>
<math>E_e = \frac{1}{2} \times 400 \times 0.25</math>
<math>E_e = 50J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and solve.'''
<math>E_e = \frac{1}{2} k x^2</math>
<math>E_e = \frac{1}{2} \times 45 \times 30^2</math>
<math>E_e = \frac{1}{2} \times 45 \times 900</math>
<math>E_e = 20250J</math>
<math>E_e \approx 20,000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and solve.'''
<math>E_e = \frac{1}{2} k x^2</math>
<math>E_e = \frac{1}{2} \times 0.80 \times 9.0^2</math>
<math>E_e = \frac{1}{2} \times 0.80 \times 81</math>
<math>E_e = 32.4</math>
<math>E_e \approx 32J</math>
|}