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## Work and Energy (part 2)

It is important to use units of measure when performing work in science. In the United States, we use the Imperial System for day-to-day conversation. But in science, the SI system is used. As an example, a Newton is a unit of force, like a pound. Newton’s are a measure of force. Another important unit of measure is the Joule. Joules are a measure of energy (or work).

#### Videos

1:33 What is a Pulley? – Simple Machines | Mocomi Kids

2:49 What Is an Advantage & Disadvantage of Movable Pulleys? : Chemistry & Physics

5:34 Simple Machines (1 of 7) Pulleys; Defining Forces, Distances and MA, Part 1

#### Compare Contrast and Debate

Background: There are three fundamental machines (the wheel, lever, and inclined plane) – but often there are three additional machines included in the list of “basic machines.” The additional three are the wedge, screw, and the pulley. Sometimes, only the first three are included when teaching about basic machines (or, basic tools). Other times all six are included. What do you think should be introduced as a basic machine?

• Position A: Really, the wedge and screw are just modified examples of an inclined plane. And the pulley is a modification of the wheel. So introducing the three most basic machines is the most important.
• Position B: while the addition of the wedge, screw, and pulley are modifications of the original three, they remain basic tools from which so many complicated machines are made, that it is important to include all six when introducing the topic of basic machines.

#### Instructor Resources

###### Standard Daily Material
• Day 1 – Standard material – introduction day
• Day 2 – Standard material – reading day
• Day 3 – Standard material – make a presentation
• Day 4 – Standard material – give a presentation
• Extra! – Enrichment and remediation options

#### Special Notes and Notices

Instructor Emphasis:

• Science & Engineering Practice: Construct explanations and design solutions.
• Cross-Cutting Concept: Systems and System Models.
###### Standards Concepts
• Energy can be transferred within a system. Regardless of what happens within a system, the total amount of energy in the system remains the same unless energy is added to or released from the system.
• Energy can be transformed (converted) within a system.
• Energy can be transferred from one system to another (or from a system to its environment) in different ways: by conduction, mechanically, electrically, or by radiation (electromagnetic waves).
• Regardless of what happens within a system, the total amount of energy in the system remains the same unless energy is added to or released from the system.