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Study Kinetic Energy with a Rube Goldberg Machine

Summary

Grade Range
6th-8th
Group Size
3-5 students
Active Time
Part 1: 1 h Part 2: 1h 40min
Total Time
Part 1: 1 h Part 2: 1h 40min
Area of Science
Physics
Key Concepts
Kinetic energy, engineering design process
Credits
Sabine De Brabandere, PhD, Science Buddies
How To Build a Rube Goldberg Machine

Overview

Rube Goldberg machines—machines that complete a simple task in a convoluted way—are intriguing, artistic, and fun! In this lesson, students will design and build such a machine themselves and use the concept of kinetic energy in the process. Before students start designing, they will do an experiment that explores how kinetic energy depends on the mass and the speed of the moving object. With a clear understanding of this concept, students then tackle the engineering design process. Watch how students channel their creative energy into constructing a fun and exciting machine!

Learning Objectives

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Science & Engineering Practices Asking Questions and Defining Problems. Define a design problem that can be solved through the development of an object, tool, process or system and includes multiple criteria and constraints, including scientific knowledge that may limit possible solutions.

Analyzing and Interpreting Data. Construct and interpret graphical displays of data to identify linear and nonlinear relationships.
Disciplinary Core Ideas PS3.A: Definitions of Energy. Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed.

ETS1.A: Defining and Delimiting Engineering Problems. The more precisely a design task's criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other relevant knowledge that are likely to limit possible solutions.

ETS1.B:: Developing Possible Solutions. A solution needs to be tested, and then modified on the basis of the test results, in order to improve it.
Crosscutting Concepts Scale, Proportion, and Quantity. Proportional relationships (e.g. speed as the ratio of distance traveled to time taken) among different types of quantities provide information about the magnitude of properties and processes.

Materials

Part 1: Experimental Exploration of Kinetic Energy

 Materials needed to explore how kinetic energy of a moving object changes with speed and mass.

Per group of 3–4 students:

Part 2: Building a Rube Goldberg Machine

 Materials for building Rube Goldberg machine

This is an engineering design project, so there is not a specific list of required materials. You can make different materials available to your students or allow them to bring materials from home. In general, recycled items, craft supplies, and office supplies work well.

Options for materials to construct parts:

Options for materials that connect parts:

Options for materials that roll:

Options for adding chemistry:

Background Information for Teachers

This section contains a quick review for teachers of the science and concepts covered in this lesson.

Kinetic energy, also called the energy of movement, is the amount of energy an object has due to its mass and its speed. In science, energy refers to the ability to create change (e.g. lift an object, deform an object, warm up a material, etc). The change a moving object can create is a measure of its kinetic energy. In this lesson, students will roll marbles down a ramp and use the distance over which a cup placed in the marble's path can be pushed as a measure of the marble's kinetic energy. Increasing the number of marbles allows students to study the impact of mass. Students will see that kinetic energy is proportional to mass. Students know this from experience, as they know that a heavy brick falling onto a foot can create more damage compared to a light plastic brick falling onto a foot from the same height.

Letting the marble(s) roll from different heights along the ramp, together with a graph showing the correlation between starting position and speed, allows students to explore how kinetic energy correlates with the speed of an object. A detailed analysis of the data will reveal that kinetic energy is proportional to the square of the speed of the moving object, or, for less mathematically inclined classes, that that kinetic energy quadruples when the speed doubles. Students also know this from experience, as they know that objects that move faster can create a lot more damage and thus, have a lot more kinetic energy. A shopping cart crashing at a slightly higher speed into a car can do a lot more damage than a shopping car that slowly rolls into a car. Or, a small increase in a car's speed quickly creates a much more severe car crash.

Once students have explored the concept of kinetic energy, they will use it to design a Rube Goldberg machine. Rube Goldberg machines are named after the American cartoonist, author, engineer, and inventor Rube Goldberg (1883-1979). According to Webster's New World Dictionary, a Rube Goldberg machine is "a comically involved, complicated invention, laboriously contrived to perform a simple operation." Rube Goldberg drew many of these machines. Usually, they are a series of simple contraptions, each of which triggers the initiation of the next, achieving the completion of a simple task in a convoluted and complicated way.

Many concepts studied in physics can be explored using Rube Goldberg machines; this lesson highlights kinetic energy. Several of the simple contraptions will have moving parts, and kinetic energy is often an accessible way to understand why they can trigger the next contraption, and if needed, how to make adjustments. For example, a sickle will need to swing fast enough, or be heavy enough, to have the energy it takes to cut a rope. A marble will need to roll fast enough or be heavy enough to have enough energy to knock over a domino. Students will use the concept of kinetic energy in the planning phase, the iterative improvement phase, and while communicating their results.

Prep Work (10 minutes)

Engage (20 minutes)

Explore (45 minutes)

Reflect (20 minutes)

Assess

Make Career Connections

Lesson Plan Variations

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