Required Practical Activity 6 - Investigate the relationship between force and extension of a spring

Question 1

Ways to avoid errors (when investigating the link between force and extension of a spring):

Answer 1

• 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

Question 2

Method for investigating the link between force and extension of a spring:

Answer 2

1. 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
2. Measure original length of spring with ruler - make sure 0cm on rules level with top of spring
3. Add 1N weight to bottom of spring
4. Measure extended length of spring using rules
5. Calculate extension of spring, extension = extended length of spring - original length of spring
6. Repeat up to 8N in 1N increments
7. For each new force measure the extension and calculate the extension of the spring
8. Plot a graph of Force vs Extension using results

Question 3

Apparatus used for investigating the link between force and extension of a spring:

Answer 3

• Clamp stand
• 2 clamps
• 2 bosses
• 7 1N weights
• Metre rule
• Spring
• pointer
• set square

Question 4

Results for investigating the link between force and extension of a spring:

Answer 4

• 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

Question 5

Independent variable for investigating the link between force and extension of a spring:

Answer 5

• The weights
• 1N – 7N
• Measured in Newtons

Question 6

Dependent variable for investigating the link between force and extension of a spring:

Answer 6

• 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

Question 7

Control variables for investigating the link between force and extension of a spring:

Answer 7

• spring
• type of weight
• metre rule
• clamp stand
• clamps
• bosses
• pointer
• set square
• the person taking the measurement

Question 8

How to increase the reliability for investigating the link between force and extension of a spring:

Answer 8

repeat the experiment multiple times and find the average to reduce the scope for error

Question 9

How to increase the validity for investigating the link between force and extension of a spring:

Answer 9

• control more variables

Question 10

What is a parallax error?

Answer 10

An error in perspective

Question 11

Definition of resolution:

Answer 11

Accuracy

Question 12

(Shows a picture of a spring with mass added)

State two ways in which the spring has changed:

Answer 12

• it has extended
• the coils have got further apart as the gap between the coils has increased

Question 13

Risk assessments for practical:

Answer 13

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