Chapter 7: Energy & Energy Transformations Week 1 Chapter 7: Energy & Energy Transformations

What is Energy? March 22- 23

Today’s Objectives Students will be able to: Identify kinetic energy and potential energy. • Identify different types of potential energy. • Explain how mass relates to an object’s kinetic energy.

Today’s Science Practice Science and Engineering Practices Asking questions and defining problems. Developing and using models. Planning and carrying out investigations. Analyzing and interpreting data. Using mathematics and computational thinking. Constructing explanations. Engaging in argument from evidence. Obtaining, evaluating, and communicating information.

What is Energy? Energy is the ability to cause change. Energy can cause an object to change its position or its motion. When was the skateboarder’s speed the greatest? When was the skateboarder’s kinetic energy the greatest?

Kinetic Energy—Energy of Motion Energy due to motion is kinetic energy. The kinetic energy of an object depends on its speed and mass. The faster an object moves, the more kinetic energy it has. What is mass? How did the kinetic energy change when we increased the skateboarder’s mass? If two objects move at the same speed, the object with the greater mass will have more kinetic energy.

Kinetic Energy—Energy of Motion How could a truck moving at the same speed as a car have more kinetic energy?

Potential Energy—Stored Energy Potential energy is stored energy. What did you observe about the skateboarder’s potential energy? There are multiple types of potential energy. When you are holding a book, energy is stored between the book and Earth; This type of energy is called gravitational potential energy. Gravitational potential energy is stored between an object and Earth depends on the weight and height of the object.

Elastic Potential Energy Elastic potential energy is energy stored in objects that are compressed or stretched. When you stretch a rubber band, you are storing elastic potential energy. When you let go of the rubber band, the stored potential energy is transformed into kinetic energy.

Chemical Potential Energy Food has chemical potential energy, which is the energy stored in the bonds between atoms. This energy is released when chemical reactions occur. How are the calorie contents of various foods related to their potential energy?

What are some real life examples of… gravitational potential energy? elastic potential energy? chemical potential energy?

Work & Energy March 24

Objectives Students will be able to: Identify when work is being done. • Describe the relationship between work and energy.

Energy & Work Work is the transfer of energy that occurs when a force is applied over a distance. Work depends on both force and distance. You only do work on an object if that object moves. Did I do work when I lifted the book? Did I do work when I held the book in the air? What is the difference between work and energy? 1. Yes. 2. No, there is no change in position. 3. Work is the transfer of energy. When work is done on an object, the object’s energy increases. When work is done by an object its energy decreases.

Energy & Work The girl does work on the box as she lifts it. The work she does transfers energy to the box. The colored bars show the work that the girl does (W) and the box’s potential energy (PE).

Wrap Up What did we learn today? How does work relate to energy? Big idea: Energy is the ability to cause a change in an object or process. Energy is transferred from object to object and/or transformed from one form to another. Work is the transfer of energy that occurs when a force makes an object move in the direction of the force.