Lesson 8 Energy Conversions

  The Steam Engine

When steam is created, the pressure can be controlled and directed in a way that can produce mechanical motion.

A steam engine is a machine that creates steam and converts the steam pressure into mechanical motion.
The development of the steam engine is a fantastic example of how trial and error can lead to major breakthroughs and understandings in science.

Click on each step of the following timeline to read about the sequential steps that led to the modern steam engine.

You can also view this interactive by visiting the Online Resources for Print Students section of your online course.

The Laws of Thermodynamics

As the invention of the steam engines progressed, and James Watt made improvements on the steam engine design and use, scientists began to search for concepts and theories that could explain the observations that were being made.

As is often the case, many scientists contributed to the experiments and collection of data that led to a new field of physics: thermodynamics.

In Lesson 1 of Section 1 of this unit, you learned about James Prescott Joule, and how he was performing experiments that investigated the relationship between potential energy and heat, as well as experiments that connected kinetic energy and heat. Joule was the first to create interest in this field of study.

The collective findings and discoveries were formulated into the laws of thermodynamics.


This first law of thermodynamics is really just a re-statement of the law of conservation of energy, with the specified form of energy being heat.

In natural processes, the direction of thermal energy flow is the same—heat always flows from a hot object to a cold object.

What do these laws essentially mean?

The total amount of energy in the universe is constant. But, no energy process is 100% efficient. The amount of energy may not change, but during energy conversions, thermal energy is produced and given off as heat. This heat is often considered to be “waste” energy.

Limiting how much of this “waste” energy is produced is what leads us to look at the efficiency of a conversion process.

  Read This

Please read pages 199 to 203 and 206 to 211 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the differences between the first and second laws of thermodynamics, and the development of the steam engine. Remember, if you have any questions, or do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

1. Explain how the trial and error involved in the invention of the modern steam engine is an example of the
   Scientific Method

   The process of scientific investigation:
   
   

   1. Identify the theory or ideas behind the experiment. What do you need to know before starting?
   2. Create a focused question you want to test. If your question is too broad you will not be able to create an experiment to test it properly.
   3. Create the experiment.
   4. Decide how to collect and record the data or evidence from the experiment. For example, is a table going to work or should you take a picture?
   5. Review the evidence and data and determine what it means. Did it answer your question? If so, what is the answer? If not, what can you change to get an answer?
   scientific method.
   
   
   Check your work.
   

   Your answer should be a variation of the following. The scientific method is a process for experimentation to discover cause and effect relationships by asking questions, carefully gathering and examining the results, and seeing if all the available information can be combined into a logical conclusion. Even though we know the scientific method is a series of steps, new information or thinking might cause a scientist to back up and repeat steps at any point during the process. The development of the steam engine shows many people going through this process.

2. When you place a metal spoon into a hot cup of tea, the spoon will become hot to the touch. Using the law of thermodynamics, explain why this is.
   
   
   Check your work.
   

   Your answer should be a variation of the following. The first law states that energy cannot be created nor destroyed, but can be transferred from one object to another. The second law explains that heat energy moves from a hot object to a cold object.