Contextualization and Project Introduction

Introduction

Elastic Force is one of the various situations we deal with in our daily lives that involves the concept of Physics. You have probably stretched a rubber band, an elastic, or even a spring at some point and noticed that the more you stretch it, the more effort is needed to keep stretching it. This happens due to a property of materials called 'elasticity'.

In Physics, the law that describes elastic force is known as Hooke's Law, which states that the force a spring exerts is proportional to how much it is stretched or compressed. In other words, if we double the extension of the spring, the force it exerts will also be doubled.

Understanding this law and knowing how to apply it is the first step to understanding the Work of Elastic Force, which is the central theme of this project.

Contextualization

The concept of Work of Elastic Force is not only useful for understanding the behavior of stretched springs or rubber bands, it also has numerous practical applications in the real world. It is used, for example, in the design of car suspensions, in civil engineering, in bridge construction, in the toy industry (think of water guns or toy airplanes with propellers that are powered by turning a spring), and even in medicine, such as in the springs used in orthodontic appliances.

Furthermore, the notion of elastic potential energy (i.e., the energy an object has due to its position in an elastic force field) is fundamental for understanding many mechanisms in physics, from the motion of planets to particle physics.

Practical Activity

Activity Title: Elastic Catapult

Project Objective

The objective of this project is to apply the theory of Hooke's Law and the Work of Elastic Force in building a catapult with springs (elastics), in order to understand how elastic force is employed and its work is carried out in practice. The purpose is to make predictions about the range of projectiles and compare them with the results obtained experimentally.

Detailed Project Description

Students will be divided into groups of 3 to 5 members. Each group will build a catapult using the following materials: popsicle sticks, elastics, and a bottle cap. They will launch a small object, such as a bean, with the catapult and measure the distance reached. Then, using the theory learned about elastic force and Hooke's law, they will try to predict the distance the bean would reach if the catapult were adjusted for different forces.

The activity should be carried out over the course of a week, with an estimated 2 to 4 hours of work per student.

Required Materials

1. Popsicle sticks (about 20)
2. Elastics (about 10)
3. Bottle cap
4. Bean or other small object to be the projectile
5. Ruler or tape measure to measure the distance
6. Paper and pen to record measurements

Activity Steps

1. Build the base of the catapult with popsicle sticks and elastics. The base should be strong enough to withstand the tension of the elastics.

2. Use more popsicle sticks and elastics to build the arm of the catapult. The arm will be used to launch the bean.

3. Attach the arm of the catapult to the base with elastics. Make sure the arm can move freely.

4. Place the bottle cap at the end of the catapult arm. The cap will serve as a container for the bean.

5. Ready? Now it's time to test the catapult. Place a bean in the bottle cap and stretch the catapult arm. Release the catapult arm to launch the bean.

6. Measure the distance the bean reached. Record this distance.

7. Repeat the launch several times, recording each time the distance the bean reached.

8. Now, try to predict the distance the bean would reach if you increase or decrease the elastic force (stretching the catapult arm more or less). Use the theory you learned about Hooke's law and the work of elastic force to make this prediction.

9. Test again, this time with the elastic force adjusted according to your prediction. Record the distance the bean reached.

10. Compare the predicted distance with the actual distance the bean reached. How close are the two measurements? What does this say about the accuracy of the theory of elastic force and Hooke's law?

Project Deliverables and Written Document

After completing the practical part of the project, groups should write a document reporting the entire process, in the form of a report containing four main topics:

1. Introduction: Contextualization of the theme and project objective. The relevance and application of the Work of Elastic Force should be discussed.

2. Development: Where the theory of elastic force and the research conducted by the group will be explained, detailing the activity performed, the methodology used, and the results obtained.

3. Conclusion: Should summarize the main points, explaining the lessons learned, the conclusions drawn from the project, and the analysis of the results, comparing them with the theory predictions.

4. Bibliography: Indicate the sources of knowledge that supported the project.

The project does not end with the report submission; on the contrary, students are expected to use the feedback received to improve their skills. Students should be encouraged to reflect on the process, teamwork collaboration, and to use the skills learned in future activities.