1. OBJECTIVE
This experiment explores Hooke's law and the deformation suffered by elastic bodies subjected to a force. Initially, you will observe that an elastic material, when deformed by the action of a force, returns to its original shape when the force ceases. Next, you will determine the spring constant of a spring from experimental data. Finally, you will explore the effect of combining springs in series and parallel. As part of the activities you will have to assemble and adjust the equipment and instruments necessary to carry out the experiment.


At the end of this experiment, you should be able to:

describe the influence of the elastic constant on the deformation of springs;

construct and interpret a force versus deformation graph in a spring;

relate forces and deformations in springs;

determine the elastic constant (k) of a spring, based on experimental data;

state Hooke's Law;

describe the behavior of springs when associated in series and in parallel;

calculate the equivalent elastic constant of an association of springs.

2. WHERE TO USE THESE CONCEPTS?
Countless objects present in people's daily lives are specifically designed with elastic deformation springs. Bungee-jumping is an extreme sport based essentially on the elastic property of the rope (or strap) tied to the feet of the brave. The fact that the bungee cord stretches to a certain limit and restores itself is vital to ensuring the excitement and safety of the jump.



Shock absorbers and springs are part of a motorcycle's suspension system. The springs are designed to absorb all the oscillations and irregularities of the terrain (roads) on which the motorcycle travels. A speed bump (speed bump) causes the spring to contract, while a pothole causes it to extend. In both situations, the springs absorb energy, controlled by the shock absorber, and thus soften the spring's return movements to the original position. In short, motorcycle springs absorb irregularities in the terrain, control the height of the vehicle and influence the balance of the suspension.



Several examples of the use of springs and their properties can be found in civil engineering, in seismic shock absorbers for example; in electrical engineering, electrical contactors and accessories; and in mechatronic engineering, robots and production lines.


3. THE EXPERIMENT
In this experiment you will observe the relationship between force and deformation in springs. You will use a set of masses to apply different forces to the springs, measuring their respective deformations. From the data collected, you will determine the elastic constants of the springs and verify Hooke's law. Finally, you must associate springs in series and in parallel and, using the same set of masses, determine the equivalent elastic constants of the associations.


4. SECURITY
The experiment was designed not to pose physical risks, so you will use objects that are not very harmful and light, but even with these precautions thought out and defined, the use of personal protective equipment is extremely important for safety when carrying out experiments. In this experiment, the use of a lab coat is recommended.


5. SCENARIO
The figure below illustrates the experiment to be carried out. You will find on the bench: the test base with vertical ruler, springs of different colors and elastic constants, movable support for springs, short hook to insert the weights, a 23g disc-shaped weight used to pre-tension the spring and four 50g weights used to deform the springs.