Energy - Eva Varga

While teaching STEM Club these past few weeks, I came to realize the kids were not as familiar with the forms of energy as I had predicted. I thereby decided to take a detour – exploring the differences between potential and kinetic energy in a little more depth.

We thereby did two activities this week – one to explore how the height of a swinging mass is related to its energy (or ability to do work) and another to explore how wind generates mechanical energy. I am excited to share these activities with you today.

Swing It!

Experimental Question:

How will the height from which an object falls affect the distance another object moves when struck?

Materials Needed:

Clamp or Duck Tape
50 gram mass
String
Block of Wood
Meterstick

Procedure:

Tie one end of the string to a 50 gram mass (perhaps a D-cell battery).
Attach the clamp to the edge of your table. Tie the loose end of the string to the clamp. Alternatively, you can use Duck Tape to secure the string to the edge of a table.
Adjust the string so that the mass almost touches the floor. Make a small pencil mark on the floor under the mass.
Set a block of wood on the mark. Practice swinging the mass so that it knocks the wood straight across the floor.
While keeping the string tight, pull back the mass until it is exactly 10 cm above the floor.
Let the mass swing down and hit the wood.
Measure how far it moves from the mark on the floor and record the distance in the table below.
Repeat steps 5-7 three times and calculate the average distance the block traveled.
Raise height to 15cm and finally 20cm – repeating steps 5-7 again.

Conclusion:

In what way was work done in this activity?
Where did the energy to do this work come from?
At which height was there the most energy to do the work?

Wind Powered Cars

We converted toy cars into wind-powered cars by building and attaching turbines. Students made modifications to help their cars travel as fast as possible. In the end, we evaluated the advantages and disadvantages of wind energy.

Materials Needed:

Turbine pattern printed onto card stock
Jumbo paperclip
Duct tape
Scissors
Toy car
Straw

Procedure:

Place a toy car on a flat surface. Ask students to suggest ways to make it move without touching it. Ideas may include attaching a motor or knocking something into it. If this were a real car, what would give it power? Gasoline (fossil fuels) Are there some other alternative resources we could use that are renewable? Students may be most familiar with solar energy.
Explain that students will be using wind to power a toy car.
Cut out the turbine pattern as indicated and attach to the back of the toy car as described.

Science Logic: Electricity & Magnetism

These lessons – including lab sheets with data tables, detailed instructions for how to convert the toy cars, and activities to explore watt usage at home – will be included in the Science Logic: Electricity & Magnetism unit that I hope to release by Summer 2016.

Until then, they are available as a freebie For Subscribers Only.

Last week, three local utility company employees (two of whom were linemen) spent the morning with us sharing stories and giving demonstrations about energy conservation and electrical safety. It was a fun-filled atmosphere and everyone learned something new.

zap wow

While the lineman were giving their presentation and interacting with the kids, I was as giddy as a school girl. I recognized the electrical “toy” on the table and was eager to play with it and allow the kids the same opportunity. As a former teacher in a public school, I had had some experience with a Van de Graaff generator, a device that looks like a big aluminum ball mounted on a pedestal, as a source of artificial high-voltage discharges. They are great fun in the classroom because when you touch the ball, it makes your hair stand on end as the negatively charged particles build up and push away from one another. But as a homeschool mom, a Van de Graaff generator just isn’t in our homeschool budget. I was in for a surprise, however, for the device was not what I thought it was – it was a higher voltage Tesla coil.

Van de Graaff Generator

To understand the Van de Graaff generator and how it works, you need to understand static electricity. Almost all of us are familiar with static electricity because we can see and feel it in the winter. On dry winter days, static electricity can build up in our bodies and cause a spark to jump from our bodies to pieces of metal or other people’s bodies. We can see, feel, and hear the sound of the spark when it jumps. You may have also done some experiments with static electricity.

A Van de Graaff generator is a device designed to create static electricity and make it available for experimentation. The American physicist Robert Jemison Van de Graaff invented the Van de Graaff generator in 1931. The device that bears his name has the ability to produce extremely high voltages — as high as 20 million volts. Van de Graaff invented the generator to supply the high energy needed for early particle accelerators. These accelerators were known as atom smashers because they accelerated sub-atomic particles to very high speeds and then “smashed” them into the target atoms. The resulting collisions created other subatomic particles and high-energy radiation such as X-rays. The ability to create these high-energy collisions is the foundation of particle and nuclear physics.

Van de Graaff generators are described as “constant current” electrostatic devices. In the case of the Van de Graaff generator, as you approach the output terminal (sphere) with a grounded object, the voltage will decrease, but the current will remain the same. Conversely, batteries are known as “constant voltage” devices because when you put a load on them, the voltage remains the same. A good example is your car battery. A fully charged car battery will produce about 12.75 volts. If you turn on your headlights and then check your battery voltage, you will see that it remains relatively unchanged (providing your battery is healthy). At the same time, the current will vary with the load. For example, your headlights may require 10 amps, but your windshield wipers may only require 4 amps. Regardless of which one you turn on, the voltage will remain the same.

Tesla Coil

A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. Tesla coils can produce higher voltages than electrostatic machines like the Van de Graaff generator described earlier. Tesla used these coils to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires.

The lineman demonstrated the coil but didn’t offer the kids a chance to try it for themselves. When most had departed though, I approached and inquired if I couldn’t give it a go. I was in for quite the shock!

If you are interested in exploring electricity in more depth in your homeschool, I encourage you to reach out to your local schools. It may be possible to visit a science lab at your local middle school or high school to experience a Van de Graaf generator first hand. Many science centers also have them and even if not on public display, may be willing to organize a special class for a group of homeschoolers. Alternatively, contact your local utility company as I did. They may have special programs they can bring to your co-op. You won’t know if you don’t ask.

In STEM Club, we are immersed in energy resources presently – so a field trip to a hydroelectric dam is the perfect field trip. Shasta Dam, the 2nd largest dam in the country (after Grand Coulee in Washington state) is in our backyard – so it is the perfect field trip.

Hydro Dams Shasta Dam is a curved gravity dam across the Sacramento River in the northern part of the U.S. state of California, at the north end of the Sacramento Valley. Like another curved gravity dam (Hoover Dam), it was a continuous pour concrete project, and in its day, ranked as one of the great civil engineering feats of the world. The dam is 602 ft (183 m) high and 3,460 ft (1,055 m) long, with a base width or thickness of 543 ft (165.5 m). The reservoir created behind Shasta Dam is known as Shasta Lake and is a popular recreational boating area.

generator at shasta dam

Hydroelectric power is universally known as one of the cleaned, most efficient and inexpensive ways to produce power. Hydroelectric power is electricity generated using falling water. At Shasta Dam, as water races down pipes (penstocks) towards the power plant, that water is directed at the blades of a water wheel (turbine).

The turbine is coupled to an electric generator by a long shaft. The generator consists of a large, spinning “rotor” and a stationary “stator”. The outer ring of the rotor is made up of a series of electromagnets. The stator is comprised of a series of copper coils. As the rotor spins, its magnetic field induces a current in the stator’s windings thereby generating electricity.

The five generators at the Shasta Dam have recently been upgraded by the Bureau of Reclamation, replacing the turbine portion of each generator. This increases the plant capacity to 710 megawatts, with each unit running at 142 megawatts. Utilizing the latest technology in design, the new turbines are more energy efficient.

Our visit this past week to the dam was not our first. We toured the Shasta Dam facilities when we first moved to California. Even so, we all learned something new and enjoyed the experience. One of the highlights was discovering that since the Shasta Dam is a curved gravity dam, we could hear our echo bounce back and forth when we yelled across the span. Additionally, one our first tour, we were most impressed by the train tunnel – as my son was passionate about trains at that age. He is now more impressed with engineering marvels and as a result, he stayed close to the tour guide the entire time asking many questions.

Minecraft Model Shasta Dam When we returned home, he created a model of the dam in one of his Minecraft worlds. Proving once again that Minecraft is educational. He is now brainstorming ideas to create a three dimensional model showing how electricity is generated and transmitted to our homes.

If you are interested in touring a dam in your area or simply learning about dams from the comfort of your home – I have created a FREE set of notebooking printables to guide you along on your study. These printables are a small part of my newest mini-unit, Alternative Energy Resources: Hydroelectric Dams, a 13 page ebook available for purchase in my store. In the coming months, I will be releasing a complete curriculum for energy resources.

Energy is the driving force for the universe. We think of energy as the ability of a system to do work. Work is a force applied to an object over a certain distance, such as pulling or pushing a book across the surface of your desk. Your muscles do work when they enable body movement.

“Energy makes things go, makes things run, makes things move, makes things fun!”
~ Bill Nye

Forms of Energy

Energy can be classified as either potential (stored energy) or kinetic (energy of motion) yet it can take many different forms. One form of energy can be changed to another form. The laws of thermodynamics govern how and why energy is transferred. Before the different types of energy resources and their uses are discussed, it is important to understand a little about the basic laws of energy.

By definition, work is an energy requiring process. So, how do you describe energy? Energy is not a substance that can be held, seen, or felt as a separate entity. We cannot create new energy that is not already present in the universe. We can only take different types of materials in which energy is stored, change their state, and harness the energy in order to use it to do work for us. If the released energy is not harnessed, it will generally change to heat energy and “wasted”.

The first law of thermodynamics, also called conservation of energy, states that the total amount of energy in the universe is constant. This means that all of the energy has to end up somewhere, either in the original form or in a different from. We can use this knowledge to determine the amount of energy in a system, the amount “lost as waste” heat, and the efficiency of the system.

After discussing these concepts briefly in class, we dived into a lab activity to explore in more depth how we can convert the potential chemical energy inside a battery to kinetic energy by creating a very simple motor.

Simple Motors Lab

Materials (per child):

1 D-cell battery
1 meter of 20-22 gauge enameled copper wire
1 rectangular ceramic magnet
2 large paper clips
masking tape

Procedure:

Hold the wire so that approximately 5cm extends beyond the tip of your fingers.
Wrap the remaining wire around two fingers until about the same length of wire extends below your fingers.
Wrap one of the “tails” around the coil to tie it together at the narrow end of the oval.
Do the same with the other “tail” so that the coil is held together. A well-made coil can rest on its “tails” between two outstretched fingers and spin easily.
Sand all the insulation off the wire on one of the “tails” (it will be a bright copper color where the insulation has been removed). On the other “tail” only sand the insulation off about half way around the wire. On both “tails”, make sure you sand right up to the coil.
Take the safety pins onto the end of the battery and stick the magnet to the battery. Make sure the holes in the safety pin line up.
Rest the coil in the loop of the two safety pins.
Give the coil and gentle spin and your motor should start turning on its own.

Trouble Shooting:

Make sure the coil is well balanced so that it spins freely when resting on the pins.
Make sure that your sanding job was good. All sanded areas should show bright copper.
Hold the safety pins to the battery with your fingers to make sure they are contacting the battery at the terminal ends.

After you get the motor to work, try doing either of the following:

Make the motor go faster.
Make the motor go in reverse.

As you work on your motor, record what you want to do in the form of a question. After each question, note what you did and what you observed. For example, you may want to ask a question like: How will the shape of the coil affect the speed of the motor?

Science Logic: Electricity & Magnetism

This lesson will be included in the Science Logic: Electricity & Magnetism unit that I hope to release by April 2014. In addition to the simple motor illustrated here, instructions for a simple speaker and simple generator will also be provided.

I’ve also created several notebooking pages … you can get a glimpse of

For the past several weeks, we have been exploring electricity and magnetism as a part of our GEMS class. This week’s lesson focused upon the production of electricity. In other words, how is electricity generated on a large scale for community consumption? What are the benefits of generating electricity in this way? What are the risks?

To begin, I provided the kids with just a few simple materials (a D cell battery, 1m of copper wire, 2 large paper clips, and a magnet). With these materials, the kids worked to create a simple motor. Illustrated step-by-step instructions were provided and when they encountered problems, suggestions were made. Most of the students were successful eventually, though there we did experience a little frustration as well leading me to believe that perhaps the activity was too difficult for this age.

While they worked, I asked numerous questions to elicit their prior knowledge about electricity and the sources by which it is generated. The kids were aware of only three: wind, water, and fossil fuels. With each, I described in detail how electricity is generated, emphasizing the common thread of a generator or huge magnet within a coil of wire that is moved back and forth rapidly.

Thereafter, I allowed each child to select an energy resource of choice with which they were instructed to create a poster to illustrate the path of electricity from it’s natural source to our home. Captions were provided so essentially, each child needed only to illustrate the steps as outlined on their paper.
Upon completion of their posters, we engaged in a discussion of the benefits and risks of each energy source. It was a successful lesson and in the days that followed, I enjoyed listening to the kids point out to their father the transformers around town.

When we drove to Portland later in the week, their interest and understanding of Detroit and Big Cliff Dams along the Santiam River were magnified. Coincidentally, the Oregon Field Guide episode that aired this week included a segment called Hot Fish, Cold Fish which looks at the impact of the dam on the ecology of the river. I just love it when our lessons coincide with unplanned life experiences.