HOOKE’SLAW
INVESTIGATION
Lab report : variables,
tables and graphs
LEARNING OBJECTIVES
We are learning to:Identify variables and use them to make a table and plot a graph
What I’m looking for:You must be able to draw a simple table to record the results of an
experiment (grade E)
You should be able to identify the control, independent and
dependent variables in an experiment (grade C)
You could be able to plot a line graph of your results (grade B)
VARIABLES
Variables –
these are all the factors that could have an effect on
the investigation
Control variables – these are the most important variables that
should be considered, they usually need to be
controlled (kept constant) to have fair test
Independent variable – this the ‘input factor’ you will be changing
and testing
Dependant variable – this is the variable you measure that depends
on the independent variable.
CHECK YOUR LEARNING: 1
Complete Task 1 on your
worksheet:
Using 2 different colours, highlight
the independent and the
dependent variables in the 9
investigation aims listed.
BASIC THEORY OF HOOKE’S LAW
When a force is
exerted on a spring
it will either
compress (push the
spring together) or
stretch the spring if
the weight is hung
on it.
INVESTIGATION
An investigation into how the amount of
mass affects the extension of a spring
In this experiment the extension of the spring is
measured with increasing weights being added 1N,
2N, 3N to 5N.
The extension is a measure of how much the spring
stretched. (Not the total length of the spring)
Independent variable
Mass (g) going up in 100 grams
Dependent variable
Extension (cm)
Control variable
Forcemeter, spring, same set of
masses.
HOW TO DRAW A GOOD TABLE
1. Always use squared or ruled paper
2. Always use a ruler
3. The independent variable goes in the first
column
4. The dependent variable goes in the next
column
5. Always have 3 repeat columns or tables
6. Always have an average
7. Always round up your results (more on this
soon!)
RESULTS OF EXPERIMENTS
Mass in g
100
200
300
400
500
extension of
spring (cm)
Try 1
extension of
spring (cm)
Try 2
extension of
spring (cm)
Try 3
Average
extension of
spring (cm)
RESULTS OF EXPERIMENTS
Mass in g
extension of
spring (cm)
Try 1
extension of
spring (cm)
Try 2
extension of
spring (cm)
Try 2
Average
extension of
spring (cm)
100
4
5
3
4
200
8
7
9
8
300
12
12
12
12
400
16
15
17
16
500
20
19
22
20
HOW TO PLOT A
GOOD GRAPH
1. Always use graph paper
2. Always use a sharp pencil
3. Make certain that the independent variable is on
the x axis and the dependent variable is on the y
axis
4. Have a suitable scale that fills the whole paper
5. Plot carefully putting an ‘x’ at each point
6. Do not join the points together using a ruler.
Add a straight line or a smooth curve that is the
best fit showing the pattern of your results.
A graph to show how a spring's length changes
with mass
18
extension of a spring cm
16
14
12
10
8
6
4
2
0
100
200
300
mass in g
400