To determine the elasticity of an elastic band by applying Hooke’s law

Hypothesis: Hooke’s Law states that the extension of an elastic body is directly proportional to the force exerted on it. However, this is only when the force does not exceed the elastic limit which would result in the deformation of the body.

Apparatus:

1) Retort stand

2) Clamp

3) Meter rule

4) Varied loads

5) Elastic band.

Diagram:

Procedures:

1) The apparatus are set up as per the diagram above except for the loads.

2) The original length of the elastic is then noted using the meter rule.

3) A mass of 20 g was then attached to the bottom of the elastic band allowing it to be hanged in air and the new length is noted.

4) The new length is then subtracted from the original one to get the extension.

5) Steps 3 and 4 are repeated variously for with new loads each time.

6) The above step is then repeated but by removing loads instead of adding then

7) In the end we are left with two graphs of mass against extension for loading and unloading. The readings obtained are found below.

Readings obtained.

Loads/g

Loading

Unloading

Length/cm

extension/cm

Length/cm

extension/cm

Unloaded

9.0

0.0

8.0

0.0

20

8.5

0.5

8.7

0.7

30

8.6

0.6

8.8

0.8

40

8.7

0.7

8.9

0.9

50

8.8

0.8

9.1

1.1

60

8.9

0.9

9.2

1.2

70

9.0

1.0

9.3

1.3

80

9.2

1.2

9.4

1.4

90

9.3

1.3

9.5

1.5

100

9.5

1.5

9.7

1.7

110

9.6

1.6

9.9

1.9

120

9.7

1.7

10.1

2.1

130

9.8

1.8

10.2

2.2

140

10.1

2.1

10.4

2.4

150

10.2

2.2

10.6

2.6

160

10.5

2.5

10.7

2.7

170

10.6

2.6

10.9

2.9

180

10.8

2.8

11.1

3.1

190

11.0

3.0

11.3

3.3

200

11.3

3.3

11.5

3.5

210

11.7

3.7

11.7

3.7

Calculations:

To find extension: new length – initial length (8cm )

Precautions:

1) While installing the meter rule as shown in the above figure, it was made sure that the meter rule was perpendicular to the retort stand’s base by using a tri-square.

2) Parallax error was avoided were placed perpendicularly with the reading/meter rule.

Improvements:

1) In order to make sure that there were no fluctuations in the elastic band, an interval of a minimum of a minute should have been allowed.

2) A pointer should have attached to the load in order to reduce parallax errors.

Mistakes:

1) After new weights were added, there were fluctuations in the elastic band whereby imprecise readings could have been noted.

2) The needle could not have been totally perpendicular to the meter rule hence parallax error could have occurred.

Conclusion:

Elastic limit was not overtaken as the loading and unloading readings were relatively equivalent. For instance, the experiment performed seemed to have obeyed Hooke’s law.