$$\require{cancel}$$

• ## Book: Physics (Boundless)

• ### 1: The Basics of Physics

• #### 1.5: Units and Measurement Redux

Physics is about trying to find the simple laws that describe all natural phenomena using a vast range of mass, length, and time scales. These scales are defined by systems of units that are built up from a small number of base units, which are set by accurate and precise measurements of conventionally chosen base quantities. Accuracy refers to how close a measured value is to an accepted reference value while precision refers to how close the agreement is between repeated measurements.

• ### 3: Vectors

Vectors are essential to physics and engineering. Many fundamental physical quantities are vectors, including displacement, velocity, force, and electric and magnetic vector fields. Scalar products of vectors define other fundamental scalar physical quantities, such as energy. Vector products of vectors define still other fundamental vector physical quantities, such as torque and angular momentum.

• ### 9: Static Equilibrium, Elasticity, and Torque

• #### 9.1: Static Equilibrium and Elasticity

The elastic properties of materials are especially important in engineering applications, including bioengineering. For example, materials that can stretch or compress and then return to their original form or position make good shock absorbers. In this chapter, you will learn about some applications that combine equilibrium with elasticity to construct real structures that last.

• ### 10: Rotational Kinematics, Angular Momentum, and Energy

• #### 10.1: Fixed-Axis Rotation Introduction

We begin to address rotational motion in this chapter, starting with fixed-axis rotation. Fixed-axis rotation describes the rotation around a fixed axis of a rigid body; that is, an object that does not deform as it moves. We will show how to apply all the ideas we’ve developed up to this point about translational motion to an object rotating around a fixed axis. In the next chapter, we extend these ideas to more complex rotational motion.

• #### 10.8: Angular Momentum

Angular momentum is the rotational counterpart of linear momentum. Any massive object that rotates about an axis carries angular momentum, including rotating flywheels, planets, and so on. Like with linear momentum, a system's total angular momentum is conserved in the absence of external torques. The conservation of angular momentum states that the angular velocity of a rigid body is inversely proportional to its moment of inertia.

• ### 11: Temperature and Kinetic Theory

• #### 11.1: Temperature and Heat

In this chapter, we explore heat and temperature. It is not always easy to distinguish these terms. Heat is the flow of energy from one object to another. This flow of energy is caused by a difference in temperature. The transfer of heat can change temperature, as can work, another kind of energy transfer that is central to thermodynamics.

• #### 11.6: The Kinetic Theory of Gases

Gases are literally all around us—the air that we breathe is a mixture of gases. Other gases include those that make breads and cakes soft, those that make drinks fizzy, and those that burn to heat many homes. Engines and refrigerators depend on the behaviors of gases, as we will see in later chapters. As we discussed in the preceding chapter, the study of heat and temperature is part of an area of physics known as thermodynamics.

• ### 13: Thermodynamics

• #### 13.1: The First Law of Thermodynamics

We will see that the first law of thermodynamics explains that a change in the internal energy of a system comes from changes in heat or work. Understanding the laws that govern thermodynamic processes and the relationship between the system and its surroundings is therefore paramount in gaining scientific knowledge of energy and energy consumption.