Force & Extension - AQA Practical

AQA GCSE Physics Force and Extension required practical: investigating the relationship between the force applied to a spring and its extension.‍ ‍Combined & Triple Science.

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A student wants to determine the relationship between the force and extension of a spring.

Plan a valid method that allows them to plot an appropriate graph.

[6 marks]

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1. Prepare

• What setup do we need?

  • Clamp stand; two bosses with clamps connected to it

  • A ruler vertically on the first clamp and a spring alongside on the second so we can measure the spring length

  • Make sure the zero mark of the ruler is level with the top of the spring

2. Measure

• What do we measure?

  • Measure the length of the spring before adding any weights to determine the original length

  • Then add known weights (1N, 2N, 3N etc) in equal increments (of 1N), recording the force in newtons and the spring's length in m after each addition - allow the spring to settle before recording each measurement.

3. Calculate

• How do we calculate extension?

  For each weight:

  • Extension (m) = stretched length (m) - original length (m)

4. Plot

• What graph do we plot?

  • Force (N) on the y axis and Extension (m) on the x axis

  • Draw a suitable line or curve of best fit.

  • The straight pink section is when Hook’s Law applies (force and extension are directly proportional here)

  • Limit of Proportionality is the point where the line is about to curve (Hooke’s Law no longer applies after this point)

Challenge:

• How do we improve reliability of the practical?

  • Repeat the measurements and calculate mean values

• How do we prevent parallax error in this practical?

  Measure the spring's length at eye level to reduce parallax error.

Continue Revising Paper 2

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