Investigating Hooke's Law
Aim
The aim of my coursework is to investigate and achieve a clear understanding into whether Hooke's law is true and to what extend in which it works and why.
Prophecy
Hooke's law states that if we add the same sized mass on to a spring its length should increase by a regular amount. For example when you double mass the extension should double. This should work until a spring reaches its elastic limit. The elastic limit of a spring is when the weight (stress) is too much and causes the spring to be permanently deformed and it does not return to its original length .The amount of deformation, as a fraction of the original size, is called strain. Elasticity is the property and the name given to a material that resumes its original size and shape after having been compressed or stretched by an external force. The elastic limit of a spring is determined by the molecular structure of the material of the actual spring. When a force is applied to the spring creating stress within the material, the molecular distances change and the material becomes deformed. Below the elastic limit, when the applied force is removed, the molecules return to their balanced position, and the elastic material goes back to its original shape. Beyond the elastic limit, the applied force separates the molecules to such an extent that they are unable to return to their original positions, and the material is permanently deformed or broken apart.
Hooke's law states that in an elastic material strain is proportional to stress this can be written as this;
S ? St
Where S = strain and St = stress
As part of preliminary work we did an experiment with long and short springs, the purpose of this was to put Hooke's law to the test and determine which spring should be used in the focal experiment. The graphs of my findings are included below;
I drew a line of best fit when I had plotted my findings and discovered that the results should be in a straight line and when I draw the line of best fit it should go through the origin of (0,0) the reason being that this was not the case was because, the springs where in a state of compression and therefore would not have followed Hooke's law to start with. This told me that when I do my focal experiment I would have to put a mass of 100g on and count this as 0g, as after 100g the spring follows Hooke's law according to the results of the preliminary experiment. The graphs also led me into thinking which spring I should use on the main experiment. The type of spring that I will be using in my investigation is the short spring because, when I examined my graphs and compared the results of the short spring against the long spring, I found out that the gap between the extensions on the long spring was larger than the gap for the short spring. In using the smaller length spring I am minimising the chance of error when I calculate the length of the spring. Also as part of my preliminary work I learnt that there was other things that affected the extension of a spring these were;
Aim
The aim of my coursework is to investigate and achieve a clear understanding into whether Hooke's law is true and to what extend in which it works and why.
Prophecy
Hooke's law states that if we add the same sized mass on to a spring its length should increase by a regular amount. For example when you double mass the extension should double. This should work until a spring reaches its elastic limit. The elastic limit of a spring is when the weight (stress) is too much and causes the spring to be permanently deformed and it does not return to its original length .The amount of deformation, as a fraction of the original size, is called strain. Elasticity is the property and the name given to a material that resumes its original size and shape after having been compressed or stretched by an external force. The elastic limit of a spring is determined by the molecular structure of the material of the actual spring. When a force is applied to the spring creating stress within the material, the molecular distances change and the material becomes deformed. Below the elastic limit, when the applied force is removed, the molecules return to their balanced position, and the elastic material goes back to its original shape. Beyond the elastic limit, the applied force separates the molecules to such an extent that they are unable to return to their original positions, and the material is permanently deformed or broken apart.
Hooke's law states that in an elastic material strain is proportional to stress this can be written as this;
S ? St
Where S = strain and St = stress
As part of preliminary work we did an experiment with long and short springs, the purpose of this was to put Hooke's law to the test and determine which spring should be used in the focal experiment. The graphs of my findings are included below;
I drew a line of best fit when I had plotted my findings and discovered that the results should be in a straight line and when I draw the line of best fit it should go through the origin of (0,0) the reason being that this was not the case was because, the springs where in a state of compression and therefore would not have followed Hooke's law to start with. This told me that when I do my focal experiment I would have to put a mass of 100g on and count this as 0g, as after 100g the spring follows Hooke's law according to the results of the preliminary experiment. The graphs also led me into thinking which spring I should use on the main experiment. The type of spring that I will be using in my investigation is the short spring because, when I examined my graphs and compared the results of the short spring against the long spring, I found out that the gap between the extensions on the long spring was larger than the gap for the short spring. In using the smaller length spring I am minimising the chance of error when I calculate the length of the spring. Also as part of my preliminary work I learnt that there was other things that affected the extension of a spring these were;
