Forces
Force and Extension Required Practical
To investigate the relationship between force and extension and use a graph to find a spring’s spring constant.
What you will learn
How to set up the force–extension practical
How to measure force and extension accurately
How to control variables and repeat readings
How to plot and interpret a force–extension graph
How to find spring constant and spot anomalies
Explanation
Measure a spring’s original length and its length under increasing known loads. Calculate extension, plot force against extension and find the spring constant from the straight section’s gradient. Keep the spring and measuring arrangement fixed, read at eye level and use a secure stand with precautions against falling masses. Example: Length changes from 12 cm to 17 cm. Find extension in metres. 0.05 m. A correct answer needs an appropriate unit as well as a numerical value. Justify your answer.