5.3.5 Required Practical: Investigating Force & Extension

• What is the aim of the investigation described in the study material?

  To investigate the relationship between the force applied to a spring and its extension, and to determine whether the spring obeys Hooke’s Law.
• What equipment is needed for the investigation?

  • A spring (with a known spring constant, k)
  • A clamp stand and clamp
  • A set of known masses (weights)
  • A ruler or measuring device (e.g., a vernier caliper)
  • A spring balance (optional)
  • A pointer (optional)
• How should the spring be set up for the experiment?

  The spring should be secured vertically using the clamp stand and clamp, hanging freely.
• What is the first step in measuring the spring's extension?

  Measure and record the natural length of the spring without any weights attached.
• What should be done after measuring the initial length of the spring?

  Gradually add known masses to the spring in increments to measure different force levels.
• How do you calculate the extension of the spring?

  By subtracting the initial length from the new length after adding weights.
• What formula is used to calculate the force applied to the spring?


  F = m × g, where m is the mass in kilograms and g is the acceleration due to gravity.
• Why is it important to return the spring to its original length before adding new weights?

  To ensure accurate measurements of extension for each weight added.
• What should be included in the data table created during the experiment?

  • Mass
  • Force
  • Extension
  • Any other relevant data
• What is the purpose of plotting a graph of force against extension?

  To observe a linear relationship that indicates whether the spring follows Hooke’s Law.
• How can the spring constant be determined from the graph?

  By calculating the gradient of the linear portion of the graph.
• What does a straight line through the origin on the graph indicate?

  It indicates that the spring obeys Hooke’s Law.
• What does it mean if the graph deviates from a straight line?

  It indicates that the spring has exceeded its elastic limit and does not follow Hooke’s Law in that region.
• What are the conclusions that can be drawn from the experiment?

  • If the graph is linear, it confirms that the spring follows Hooke’s Law.
  • The gradient of the graph gives the spring constant, indicating the stiffness of the spring.
• What safety considerations should be taken during the experiment?

  • Ensure weights are securely fastened.
  • Ensure the setup is stable to avoid accidents.
• What accuracy considerations should be made during the experiment?

  • Use precise measurements.
  • Avoid parallax errors when measuring lengths.
  • Ensure weights are calibrated and consistently applied.
• What is an example of data that could be recorded in the experiment?

  • Mass (kg)
  • Force (N)
  • Extension (m)
• What is the approximate value of the acceleration due to gravity used in calculations?

  Approximately 9.8 m/s².
• What is the overall objective of the experiment?

  • Investigate how force affects the extension of a spring.
  • Determine if Hooke’s Law is obeyed.
• What is the procedure for the experiment?

  1. Measure the extension of the spring with increasing forces.

  2. Plot the results.

  3. Analyze the relationship.
• What results confirm Hooke’s Law?

  • A linear graph.
  • The spring constant determined from the gradient.