# The springconstant

Springs
1 / 26
Slide 1: Slide
NatuurkundeMiddelbare schoolvmbo lwooLeerjaar 2,3

This lesson contains 26 slides, with interactive quiz, text slides and 2 videos.

Lesson duration is: 50 min

## Items in this lesson

Springs

#### Slide 2 -Slide

You know the difference between elastic and plastic deformation
You know how to calculate the springconstant
You can use a table and draw a graph

#### Slide 6 -Slide

Hook's law
Hook's law defines the linear
relationship between stress
and strain within the elastic region

Or in other words, it describes the
relationship between a force at
work on a spring and the related
extension of this spring.

#### Slide 7 -Slide

There is a constant relationship between the force at work and
the extension of a sping, as long as the spring can go back to
it's original shape (elastic deformation).

This relationship is called the springconstant.

Symbols:

F = Force [N]

x = Extension [cm]

C = The springconstant [N/cm]

Not every spring is the same, some are more stiff than others.
A stiffer spring will need more force to extend the same amount
of centimeters..its springconstant therefore will be much bigger
than the springconstant of a rather flexible spring.
C=xF
Spring constant (C)
F=CX
Formula

#### Slide 12 -Slide

1. Write a title
2. Write down what you want to research
3.  Make a table for your data
4. Use your data to make a graph
5. Determine / calculate the springconstant
6. End with your own conclusion using your data and graph about the relationship between the force on a spring and the corresponding extension.
Notebook notes

#### Slide 13 -Slide

1: Stretching a helical spring
Is the reality matching the theory.... is the extension of a spring and a rubberband  directly proportional with the force you apply?

Set the experiment up as shown in the next slide
1.  Note the position of the bottom of the coil spring.
2. Put one, two, three weights on the spring and note down the number of weights, the force on the spring and the corresponding extension (table)
3. Make a graph of your measurements
4. Option: two identical springs connected serially (or parallel)

#### Slide 15 -Slide

number of weights
mass of the weights (g)
force on the spring (N)
extension (cm)
0
0
0
0
1
50
0,5
2
3
4
5

#### Slide 16 -Slide

Graph
x (cm)
use number of mass pieces
or use Force (N)
m = 50 gram = 0,05 kg

F = m.g = 0,05 kg . 10 N/kg
F = 0, 5 N for one mass piece

#### Slide 17 -Slide

So we

1. First research if the theory is correct..
does the spring react
proportionally when you put some weight on it.

2. Then you can check if a rubber band is reacting the same way.

3. After that you can connect two springs serially to check what happens then.

#### Slide 18 -Slide

UPLOAD YOUR GRAPH(s)
for the spring and rubber band
(do make clear what the graphs represent)

#### Slide 19 -Open question

1: Building & calibrating a dynamometer
Imagine: a factory that makes measuring instruments is going to launch a new model of dynamometer that allows forces to be measured accurately. A helical spring has been chosen for the new meter. Your job is to complete the design by adding an accurate and easily readable graduated scale.

Purpose
You will be making a graduated scale
that meets certain requirements.

requirements
• The range of measurement of the dynamometer must be at least 0 N to 1 N.
• The distance between the marks on the graduated scale must represent no more than 0.1 N.
• The dynamometer must be at least as accurate as an ‘ordinary’ dynamometer.

#### Slide 20 -Slide

Notebook notes
Explain how you are going to calibrate the dynamometer.
Make a note of the practical equipment you will need.
Construct the dynamometer and give it a graduated schale
Explain how you carried out the test
Make improvements, adjust your scale if necessary

If you have to write up a report of this experiment, include:
a a photo of the setup, including the calibrated graduated scale;
b how you made the graduated scale;
c the various ways in which you tested the graduated scale;
d your conclusions: how accurate is the dynamometer?