# Common Core Achieve

## CHAPTER 5

Pushing a car that is stuck or is broken down may look like hard work. But, in the physical world, no work occurs unless the car moves. Work occurs when a force is applied to move an object over a distance. Understanding the physics behind motion, force, and work can help you to better understand how people and machines do work.

• arrow_drop_downMotion

We might think of motion as the movement of an object, such as a race car speeding toward the finish line. In this lesson you will learn how scientists define motion in the physical world. Learn that in science, motion is described not only by how fast an object is moving, but also by which direction it is traveling, and by any change in direction or speed that may occur during movement.

• arrow_drop_downForces and Newton's Laws of Motion

Motion is related to the force that is present between two objects. Newton's three laws of motion explain the relationship between the motion of an object and the forces acting on it. Learn how Newton's law of universal gravitation explains how our feet stay on the ground and how the planets in our solar system stay in orbit.

• arrow_drop_downWork and Simple Machines

Did you know that the knife you use to cut your food is a simple machine? When you use that knife to cut your food, you are doing work. In this lesson you will learn how scientists define work. You will also learn about six different types of simple machines and how these simple machines can be used together to create compound machines.

### Goal Setting

You use simple machines at home and at work every day. A knife, a screwdriver, and a pair of scissors are all examples of simple machines. Even the system set up to easily lift a garage door is a simple machine. Most things that help to make a task easier can be thought of as simple machines. Think of a task that you often do at home or at work that is difficult to perform and think of ways you can use a simple machine to make this task easier. Write down your ideas. After you have read this chapter, draw a sketch of a simple machine that might help with your task and explain how it will make the task easier.

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