Required practical - investigating force and extension using a spring
Investigate the relationship between force and extension for a spring
There are different ways to investigate the relationship between force and extension for a spring. In this required practical activity, it is important to:
- measure and record length accurately
- measure and observe the effect of force on the extension of springs
- collect the data required to plot a force-extension graph
Aim of the experiment:
To investigate the relationship between force and extension for a spring.
Method:
- Secure a clamp stand to the bench using a G-clamp or a large mass on the base.
- Use bosses to attach two clamps to the clamp stand.
- Attach the spring to the top clamp, and a ruler to the bottom clamp.
- Adjust the ruler so that it is vertical, and with its zero level with the top of the spring.
- Measure and record the unloaded length of the spring.
- Hang a 100 g slotted mass carrier – weight 0.98 newtons (N) – from the spring, then measure and record the new length of the spring.
- Add a 100 g slotted mass to the carrier. Measure and record the new length of the spring.
- Repeat step 7 until you have added a total of 1,000 g.
Results:
Record your results in a suitable table.
| Force in N | Length in mm | Extension in mm |
| 0 (unloaded) | 22 | 0 |
| 0.98 | 52 | 30 |
| 1.96 | 83 | 61 |
| ...... | ...... | ...... |
| Force in N | 0 (unloaded) |
|---|---|
| Length in mm | 22 |
| Extension in mm | 0 |
| Force in N | 0.98 |
|---|---|
| Length in mm | 52 |
| Extension in mm | 30 |
| Force in N | 1.96 |
|---|---|
| Length in mm | 83 |
| Extension in mm | 61 |
| Force in N | ...... |
|---|---|
| Length in mm | ...... |
| Extension in mm | ...... |
Analysis:
- for each result, calculate the extension:
- extension = length – unloaded length
- plot a line graph with extension on the vertical axis, and force on the horizontal axis
- draw a suitable line or curve of best fit
- identify the range of force over which the extension of the spring is directly proportional to the weight hanging from it
Evaluation:
It is important to keep the ruler vertical. Suggest another way to improve the accuracy of the length measurements.
Hazards and control measures
| Hazard | Consequence | Control Measures |
| Equipment falling off table | Heavy objects falling on feet – bruise/fracture | Use a G-clamp to secure the stand |
| Sharp end of spring recoiling if the spring breaks | Damage to eyes and cuts to skin | Wear eye protection and gently lower each mass whilst loading the spring |
| Masses falling to floor if the spring fails | Heavy objects falling on feet – bruise/fracture | Gently lower load onto spring and step back |
| Hazard | Equipment falling off table |
|---|---|
| Consequence | Heavy objects falling on feet – bruise/fracture |
| Control Measures | Use a G-clamp to secure the stand |
| Hazard | Sharp end of spring recoiling if the spring breaks |
|---|---|
| Consequence | Damage to eyes and cuts to skin |
| Control Measures | Wear eye protection and gently lower each mass whilst loading the spring |
| Hazard | Masses falling to floor if the spring fails |
|---|---|
| Consequence | Heavy objects falling on feet – bruise/fracture |
| Control Measures | Gently lower load onto spring and step back |