The resource "Superposition" is included in the "Electrical engineering" course from Khan Academy. This resource is one of the sub-topics in the "Circuit analysis" topic area.

Surface tension accounts for many of the interesting properties we associate with water. By learning about surface tension and adhesive forces, students learn why liquid jets of water break into droplets rather than staying in a continuous stream. Through hands-on activities, students learn how the combination of adhesive forces and cohesive forces cause capillary motion. They study different effects of capillary motion and use capillary motion to measure surface tension. Students explore the phenomena of wetting and hydrophobic and hydrophilic surfaces and see how water's behavior changes when a surface is treated with different coatings. A lotus leaf is a natural example of a superhydrophobic surface, with its water-repellent, self-cleaning characteristics. Students examine the lotus effect on natural leaves and human-made superhydrophobic surfaces, and explore how the lotus leaf repels dewy water through vibration. See the Unit Overview section for details on each lesson in this unit.

Students are presented with the question: "Why does a liquid jet break up into droplets?" and introduced to its importance in inkjet printers. A discussion of cohesive forces and surface tension is included, as well as surface acting agents (surfactants) and their ability to weaken the surface tension of water. Students observe the effects of surface tension using common household materials. Finally, students return to the original question through a homework assignment that helps them relate surface tension and surface area to the creation of water droplets from a liquid jet.

Students extend their understanding of surface tension by exploring the real-world engineering problem of deciding what makes a "good" soap bubble. Student teams first measure this property, and then use this measurement to determine the best soap solution for making bubbles. They experiment with additives to their best soap and water "recipes" to increase the strength or longevity of the bubbles. In a math homework, students perform calculations that explain why soap bubbles form spheres.

In an activity that integrates science and art, students see, experience and harness the phenomenon of surface tension as they create beautiful works of art. Students conduct two experiments related to surface tension floating objects on the surface of water and creating original artwork using floating inks. They also learn historical and cultural information through an introduction to the ancient Japanese art form of suminagashi. They take the topic a step further by discussing how an understanding of surface tension can be applied to solve real-world engineering problems and create useful inventions.

Students learn about the basics of molecules and how they interact with each other. They learn about the idea of polar and non-polar molecules and how they act with other fluids and surfaces. Students acquire a conceptual understanding of surfactant molecules and how they work on a molecular level. They also learn of the importance of surfactants, such as soaps, and their use in everyday life. Through associated activities, students explore how surfactant molecules are able to bring together two substances that typically do not mix, such as oil and water. This lesson and its associated activities are easily scalable for grades 3-12.

This unit focuses on teaching students about the many aspects of biomedical engineering (BME). Students come to see that BME is a broad field that relies on concepts from many engineering disciplines. They also begin to understand some of the special considerations that must be made when dealing with the human body. Activities and class discussions encourage students to think as engineers to come up with their own solutions to some of medical challenges that have been solved throughout the history of BME. Class time iincludes brainstorming and presenting ideas to the class for discussion. Specific activities include examination of the material properties and functions of surgical instruments and prosthetics, a simulation of the training experience of a surgical resident, and an investigation of the properties of fluid flow in vascular tissue.

Students engineer and evolve digital organisms with the challenge to produce organisms with the highest fitness values in a particular environment. They do this through use of the free Avida-ED digital evolution software application. The resulting organisms compete against each other in the same environment and students learn the benefits of applying the principles of natural selection to solve engineering design problems.

The primary goal of this course is to provide a toolset for characterizing and strategizing how nonmarket forces can shape current and future renewable energy markets. The course approaches the exploration and explanation of key concepts in renewable energy and sustainability nonmarket strategies through evidence-based examples. Main topics for the course include: a sociological approach to markets, renewable energy markets, nonmarket conditions, complex systems analysis, and renewable energy technology and business environments. Because renewable energy costs are higher than fossil fuel cost per unit of energy, the main arguments in support of renewable energy, thus far, are functionally nonmarket in character, i.e., environmental (e.g., climate change), political (e.g., energy independence), and/ or social (e.g., good stewardship).

By independent study of the book Sustainable Development for Engineers (K.F. Mulder, 2006) students acquire basic knowledge about sustainable development

A transition to sustainable energy is needed for our climate and welfare. In this engineering course, you will learn how to assess the potential for energy reduction and the potential of renewable energy sources like wind, solar and biomass. You’ll learn how to integrate these sources in an energy system, like an electricity network and take an engineering approach to look for solutions and design a 100% sustainable energy system.

This course aims to give insight in the chain of hydrogen production, storage and use, and the devices involved. Electrical storage in the form of batteries will be discussed. Physical and materials science advances that are required to bring forward hydrogen and batteries as energy carriers will be highlighted.

It has become almost impossible to imagine what our lives would be like without the many benefits of packaging – just think about the different packaging and single-use items you use on a daily basis. Yet as our global population grows in size and affluence, both our collective demand for packaging materials and the waste we generate as a result will increase dramatically.

Currently, large amounts of packaging waste escape formal collection and recycling systems and eventually end up polluting the environment. Moreover, their material value is forever lost to the economy. The Ellen MacArthur Foundation estimates that uncollected plastic packaging waste alone is worth somewhere between 80 to 120 billion dollars a year.

So how can we improve packaging systems in order to capture this wasted potential? Clearly, the way we currently design, recover, and reuse packaging urgently needs a rethink!

In this course, you will learn about the design of sustainable packaging systems. To do so we will explore the design and business strategies of the circular economy.

Contrary to our current industrial model, which extracts, uses and ultimately disposes of resources, a circular economy is regenerative by design. This means that products and services are reimagined from a systems perspective in order to minimize waste, maximize positive economic, environmental and social impacts, and keep resources locked in a cycle of restoration.

This course is for you if you are interested in learning about sustainable packaging design. You’ll also benefit if you are a professional in the packaging industry and want to learn how to find circular opportunities in your work. Students – particularly in design – will be able to broaden their knowledge of circular design and business strategies.

Did you know that cities take up less than 3% of the earth’s land surface, but more than 50% of the world’s population live in them? And, cities generate more than 70% of the global emissions? Large cities and their hinterlands (jointly called metropolitan regions) greatly contribute to global urbanization and sustainability challenges, yet are also key to resolving these same challenges.

If you are interested in the challenges of the 21st century metropolitan regions and how these can be solved from within the city and by its inhabitants, then this Sustainable Urban Development course is for you!

There are no simple solutions to these grand challenges! Rather the challenges cities face today require a holistic, systemic and transdisciplinary approach that spans different fields of expertise and disciplines such as urban planning, urban design, urban engineering, systems analysis, policy making, social sciences and entrepreneurship.

This MOOC is all about this integration of different fields of knowledge within the metropolitan context. The course is set up in a unique matrix format that lets you pursue your line of interest along a specific metropolitan challenge or a specific theme.

Because we are all part of the challenges as well as the solutions, we encourage you to participate actively! You will have the opportunity to explore the living conditions in your own city and compare your living environment with that of the global community.

Life in the city relies on the smooth operation of urban logistics. Everything from retail to services, construction to waste collection rely on an efficient and reliable freight transport system. However, with the increasing pressures of urbanization, this has to be balanced with the environmental and social impacts caused by transport activity. This is the challenge of City Logistics, a field of study that has significant practical implications for the world and the cities we live in. It is not merely a question of what is involved, but what can be done about urban freight transport to improve it for the sake of economic efficiency, quality of life, and sustainability.

From a systematic scientific foundation of the field, this course will take you on a journey to learn how city logistics is understood and practiced in cities around the world. Our instructors, members of a renowned global expert network, will teach you the basics of this highly complex social system. Using their experience in real-world projects, they will illustrate how the knowledge learnt in this course is applied across industry and the public sector.

This course caters primarily to university students or professionals working in urban transport infrastructure planning or logistics management. Whether you are simply curious about the topic or you intend to develop a career in these fields, this course will give you the tools you need to understand the complexities of urban freight transport systems.

The course emphasizes the theoretical foundation, the rigorous evaluation, and a multi-disciplinary approach to this complex area. Course participants will benefit from numerous case studies of best practice in selected cities around the world, in a variety of business settings. Our emphasis on the global perspective is particularly relevant, since an understanding of local culture and political climate is an important factor in the success of any city logistics intervention. The course will provide an avenue for students to learn from their peers about the challenges faced in their respective cities, and how to apply the principles learned to the challenges faced in their own cities.

Using a household fan, cardboard box and paper towels, student teams design and build their own evaporative cooler prototype devices. They learn about the process that cools water during the evaporation of water. They make calculations to determine a room's cooling load, and thus determine the swamp cooler size. This activity adds to students' understanding of the behind-the-scenes mechanical devices that condition and move air within homes and buildings for human health and comfort.

Playing the role of engineers in collaborations with the marketing and production teams in a chocolate factory, students design a container for a jumbo chocolate bar. The projects constraints mean the container has to be a regular trapezoidal prism. The design has to optimize the material used to construct the container; that is, students have to find the dimensions of the container with the maximum volume possible. After students come up with their design, teams present a final version of the product that includes creative branding and presentation. The problem-solving portion of this project requires students to find a mathematical process to express the multiple variables in the prism’s volume formula as a single variable cubic polynomial function. Students then use technology to determine the value for which this function has a maximum and, with this value, find the prism’s optimal dimensions.

Students examine the motion of pendulums and come to understand that the longer the string of the pendulum, the fewer the number of swings in a given time interval. They see that changing the weight on the pendulum does not have an effect on the period. They also observe that changing the angle of release of the pendulum has negligible effect upon the period.

This activity demonstrates how potential energy (PE) can be converted to kinetic energy (KE) and back again. Given a pendulum height, students calculate and predict how fast the pendulum will swing by understanding conservation of energy and using the equations for PE and KE. The equations are justified as students experimentally measure the speed of the pendulum and compare theory with reality.

This activity shows students the engineering importance of understanding the laws of mechanical energy. More specifically, it demonstrates how potential energy can be converted to kinetic energy and back again. Given a pendulum height, students calculate and predict how fast the pendulum will swing by using the equations for potential and kinetic energy. The equations will be justified as students experimentally measure the speed of the pendulum and compare theory with reality.