Hooke's Law
INVESTIGATION OF HOOKE’S LAW –
AIM:
To investigate Hooke’s law by estimating the spring constant of a spring.
INTRODUCTION: Hooke’s law is a law in physics named after Robert Hooke, a British physicist who lived in the 17th century and is said to have been the first to pose the idea of this law.(wikipedia,2010) Hooke’s law states that the Force with which a spring pushes back is linearly proportional to the distance from its equilibrium (wikepedia,2010) , this can be simplified by saying that the force acting on a spring/material is directly proportional to the extension(which is how long the spring/material has become/stretched since the force was applied) of the string/material (Breithaupt, 2010). This can be expressed as an equation. F= -ke
Where F represents the Force (in N), e represents the extension (in m) and k is referred to as the spring constant (which is the stiffness of the spring and is unique for each spring) in N/m (Breithaupt, 2010). Many materials obey this law as long as the load applied on the material does not cause the material to exceed its elastic limit causing the material to loose its elasticity and become deformed even after the load applied has been removed. As the material exceeds its elastic limit the string begins to display a behaviour called “Plastic behaviour”, in some materials like glass, once it reaches its elastic limit it breaks. When represented on a graph it is seen that the after the elastic limit has been exceeded the material stops obeying Hooke’s law.
Force (N)
Elastic limit
Extension (m)
Fig. 1: Showing the behaviour of a material when its elastic limit has been exceeded.
Materials that obey Hooke’s law are referred to as “Hookean” Materials. However not all materials obey this law and they are referred to as “non-Hookean” materials, Rubber is a good example of a Non-Hookean material because its extension is dependent on
AIM:
To investigate Hooke’s law by estimating the spring constant of a spring.
INTRODUCTION: Hooke’s law is a law in physics named after Robert Hooke, a British physicist who lived in the 17th century and is said to have been the first to pose the idea of this law.(wikipedia,2010) Hooke’s law states that the Force with which a spring pushes back is linearly proportional to the distance from its equilibrium (wikepedia,2010) , this can be simplified by saying that the force acting on a spring/material is directly proportional to the extension(which is how long the spring/material has become/stretched since the force was applied) of the string/material (Breithaupt, 2010). This can be expressed as an equation. F= -ke
Where F represents the Force (in N), e represents the extension (in m) and k is referred to as the spring constant (which is the stiffness of the spring and is unique for each spring) in N/m (Breithaupt, 2010). Many materials obey this law as long as the load applied on the material does not cause the material to exceed its elastic limit causing the material to loose its elasticity and become deformed even after the load applied has been removed. As the material exceeds its elastic limit the string begins to display a behaviour called “Plastic behaviour”, in some materials like glass, once it reaches its elastic limit it breaks. When represented on a graph it is seen that the after the elastic limit has been exceeded the material stops obeying Hooke’s law.
Force (N)
Elastic limit
Extension (m)
Fig. 1: Showing the behaviour of a material when its elastic limit has been exceeded.
Materials that obey Hooke’s law are referred to as “Hookean” Materials. However not all materials obey this law and they are referred to as “non-Hookean” materials, Rubber is a good example of a Non-Hookean material because its extension is dependent on
References: Andy Darvill, 2010: GSCE Physics: Energy, Forces and Motion, Springs: Hooke’s Law and Elastic Limit http://www.darvill.clara.net/enforcemot/springs.htm (Accessed 7 December 2010) BREITHAUPT, J. (2010). Physics. Basingstoke, Palgrave Macmillan Wikipedia, 2010: Hooke’s Law, http://en.wikipedia.org/wiki/Hooke 's_law (Accessed 7 December 2010)