Required Practical Activity 6 - Investigate the relationship between force and extension of a spring Flashcards
Ways to avoid errors (when investigating the link between force and extension of a spring):
- Metre rule must be vertical, pointer and set square must be horizontal when taking the readings to make sure the readings are accurate.
- Take the readings at eye level to make sure there aren’t any parallax errors.
- The top of the spring must be at zero point on the metre rule.
- use set square to line up bottom of spring with rukes
Method for investigating the link between force and extension of a spring:
- Set up the apparatus as shown in the diagram - set up clamp stand with a clamp, hang the spring from the clamp, use a second clamp and boss to fix a metre rule alongside the spring
- Measure original length of spring with ruler - make sure 0cm on rules level with top of spring
- Add 1N weight to bottom of spring
- Measure extended length of spring using rules
- Calculate extension of spring, extension = extended length of spring - original length of spring
- Repeat up to 8N in 1N increments
- For each new force measure the extension and calculate the extension of the spring
- Plot a graph of Force vs Extension using results
Apparatus used for investigating the link between force and extension of a spring:
- Clamp stand
- 2 clamps
- 2 bosses
- 7 1N weights
- Metre rule
- Spring
- pointer
- set square
Results for investigating the link between force and extension of a spring:
- When the line of best fit is a straight line it means there is a linear relationship between force and extension (they’re directly proportional as there is straight line which goes through the origin). F=ke, so the gradient of the straight line is equal to k, the spring constant.
- When the line begins to bend, the relationship is now non-linear between force and extension (they’re no longer directly proportional) – the spring stretches for each unit increase in force, limit of proportionality
Independent variable for investigating the link between force and extension of a spring:
- The weights
- 1N – 7N
- Measured in Newtons
Dependent variable for investigating the link between force and extension of a spring:
- the extension of the spring
- this will be measured by measuring the extended length and original length using the metre rule and subtracting the original length from the extended length
- measured in metres
Control variables for investigating the link between force and extension of a spring:
- spring
- type of weight
- metre rule
- clamp stand
- clamps
- bosses
- pointer
- set square
- the person taking the measurement
How to increase the reliability for investigating the link between force and extension of a spring:
repeat the experiment multiple times and find the average to reduce the scope for error
How to increase the validity for investigating the link between force and extension of a spring:
- control more variables
What is a parallax error?
An error in perspective
Definition of resolution:
Accuracy
(Shows a picture of a spring with mass added)
State two ways in which the spring has changed:
- it has extended
- the coils have got further apart as the gap between the coils has increased
Risk assessments for practical:
Hazard - clamp (stand, boss and masses) might fall off desk
Risk - cause injury to feet
Control - use clamp to fix apparatus, stand up so that you can move out of the way, ensure the slotted masses hang over the base/foot of the stand, ensure that the boss is tightly screwed into the stand and clamp
Hazard - spring could break/come loose
Risk - damage eye
Précaution - wear safety goggles
How to increase accuracy?
- use a set square to line up the bottom of the spring with the ruler scale
- attach a horizontal pointer to the bottom of the spring so that the pointer goes across the ruler scale
