## Energy, Work & Power

**Housekeeping:**We are now studying work, power and energy in physics. We will relate this content to the human body before we do the sports science unit. This unit's going to have some math in it, so keep calculators handy.

The science fair is coming. You need to start thinking about potential topics. I don't suggest doing plant projects because you will need at least 50 plants and six weeks to experiment with them. The best suggestion is to find past projects and revise them by changing the independent variable.

**Essential Idea:**Recognize how work and power describe how energy moves through the environment.

**Content Review:**

Links: Work, Energy & Power Work, Energy & Power II Simple Machines

**Student Missions:****Mission 1: ENERGY! Where the Power Lies!**

**Mission Objectives. You should be able to:**

1. Define "energy," "work," and "power."

2. Explain how energy, work and power are related.

3. Calculate work done.

4. Correctly calculate power used.

5. Design a lab to measure work, power and energy.

Energy as defined in physics is the ability to do work. Work is defined as the movement of a force over a certain distance. The energy of an object can take many forms: thermal energy (heat), chemical energy (chemical bonds), potential energy and kinetic energy. Potential energy is stored energy, or energy of position. Kinetic energy is energy of motion. Objects are either at rest or in motion, so, generally speaking, PE can equal KE.

The equation for potential energy is

**m * g * h**. m is mass (kg), h is height (m), and g is gravity (9.8 m/s2).

The equation for kinetic energy is

**1/2 m * v2**. m is mass (kg) and v is velocity (m/s).

Usually, we look at a combination of PE & KE, which, when combined, is mechanical energy (ME).

Now let's talk about work. As stated above, work is defined as movement of an external force (F) over a particular distance (d). Work describes something that is being done to an object. The equation for work is Force (capital letter F) times distance. So Work = F*d. Force is measured in newtons (N) and distance is measured in meters (m). The unit Newton-meter (N*m) is better known as the joule (J).

Power is defined as work over time. The unit for power is the watt.

Power is defined as work over time. The unit for power is the watt.

Here are a bunch of practice problems.

**Mission 2: Machine's Way.**

**Mission Objectives. You should be able to:**

1. List and describe six simple machines.

2. Explain and determine mechanical advantage.

3. Analyze compound machines and describe them in terms of simple machines.

4. Calculate efficiency for simple and compound machines.

This is a lovely PowerPoint that takes you through all six simple machines, including mechanical advantage. If this does not satisfy your hankering for machine knowledge, you can also go here or here to learn more.

We will work on simple machines in class with this Mission.

**Mission 3: Let's Build!**

Mission Objective. You should be able to...

Mission Objective. You should be able to...

1. Construct a compound machine that works.

Your project for this unit is to construct a compound machine. The machine must have a purpose and actually work. You will work in six groups of three members each. You will be given some class time to construct the machines and you can use materials in the MakerSpace as well as whatever you can get on your own.

Go here to find examples of each type of machine. This project is due ________________.

simple_machines_rubric.xlsx | |

File Size: | 9 kb |

File Type: | xlsx |