# Ch 4: Laws of Motion: Help and Review

### About This Chapter

## Who's It For?

Anyone who needs help learning or mastering laws of motion material will benefit from the lessons in this chapter. There is no faster or easier way to learn the laws of motion. Among those who could benefit are:

- Students who have fallen behind in understanding how to perform calculations using Newton's laws of motion
- Students who struggle with learning disabilities or learning differences, including autism and ADHD
- Students who prefer multiple ways of learning science (visual or auditory)
- Students who have missed class time and need to catch up
- Students who need an efficient way to learn about the laws of motion
- Students who struggle to understand their teachers
- Students who attend schools without extra science learning resources

## How It Works

- Find videos in our course that cover what you need to learn or review.
- Press play and watch the video lesson.
- Refer to the video transcripts to reinforce your learning.
- Test your understanding of each lesson with short quizzes.
- Verify you're ready by completing the Laws of Motion chapter exam.

## Why It Works

**Study Efficiently:**Skip what you know, review what you don't.**Retain What You Learn:**Engaging animations and real-life examples make topics easy to grasp.**Be Ready on Test Day:**Use the Laws of Motion chapter exam to be prepared.**Get Extra Support:**Ask our subject-matter experts any laws of motion question. They're here to help!**Study With Flexibility:**Watch videos on any web-ready device.

## Students Will Review

This chapter helps students review the concepts in a laws of motion unit of a standard introductory physics course. Topics covered include:

- Newton's laws of motion
- Inertia, mass and weight
- The relationship between an object's velocity and state of motion
- Types of forces
- Free-body diagrams
- Determining an object's acceleration
- Identifying individual forces acting upon objects
- The effect of air resistance on falling objects
- How Newton's laws explain weight, mass and gravity
- Action and reaction force pairs
- Friction
- Hooke's law

### 1. Newton's First Law of Motion: Examples of the Effect of Force on Motion

This lesson describes Newton's first law of motion, also known as the law of inertia. The interaction between force and motion is explained. Several examples are used to discuss the implications of this law on earth and in space.

### 2. Distinguishing Between Inertia and Mass

Mass and inertia are both related to the amount of matter an object has, but they aren't exactly the same thing. In this video lesson, you'll see how mass affects an object's inertia, which in turn affects that object's motion.

### 3. Mass and Weight: Differences and Calculations

We often talk about mass and weight as if they are the same. While they are proportional to each other, they are not, in fact, the same. In this video lesson, you will learn to distinguish between the two, as well as convert one to the other.

### 4. State of Motion and Velocity

An object's state of motion describes how it is moving. But there are many ways we can describe motion, such as speed and velocity. This motion is relative to other objects around it, such as the earth, the sun, and even other stars in our galaxy.

### 5. Force: Definition and Types

Force is everywhere and it comes in a variety of sizes, directions, and types. In this video lesson, you'll identify force as well the different types of force that objects may experience.

### 6. Forces: Balanced and Unbalanced

Forces are needed to start or stop an object's motion, but can also be involved when an object is at rest or already traveling at constant velocity. In this video lesson, you'll identify the difference between balanced and unbalanced forces, understanding how they affect the movement of objects.

### 7. Free-Body Diagrams

Forces that act on an object can be drawn through special vector diagrams called free-body diagrams. In this video lesson you'll identify how to correctly represent forces in a free-body diagram through vector arrows and force labels.

### 8. Net Force: Definition and Calculations

Because forces are vectors, we can't simply add them up to get a total amount of force on an object. Instead, we calculate the net force, which is important to understand because it tells us about an object's state of motion.

### 9. Newton's Second Law of Motion: The Relationship Between Force and Acceleration

This lesson defines Newton's second law of motion. Examples are used to illustrate how unbalanced forces cause objects to accelerate. The examples are used to practice calculating acceleration and force for objects in motion.

### 10. Determining the Acceleration of an Object

Acceleration is a change in an object's state of motion. A few variables need to be identified to calculate an object's acceleration, but once we have those values, we can put them into a simple equation to find out how quickly or slowly an object's velocity is changing.

### 11. Determining the Individual Forces Acting Upon an Object

Objects constantly have forces acting on them whether they are moving or at rest. In this video lesson, you'll understand how to identify the individual forces acting on an object by reviewing the different types of forces and the use of free-body diagrams.

### 12. Air Resistance and Free Fall

Through experiments by Galileo and Newton, we can understand why all objects in free-fall experience the same acceleration, ''g''. We can also see why air resistance affects a falling object's velocity and how this can lead to a falling object reaching a terminal velocity.

### 13. Newton's Third Law of Motion: Examples of the Relationship Between Two Forces

This lesson describes Newton's third law of motion. Examples are provided to illustrate how interacting objects experience forces. The lesson explains how objects accelerate as a result of force. Applications of Newton's third law are illustrated in nature, machines, and space.

### 14. Newton's Laws and Weight, Mass & Gravity

Did you know that mass and weight are not the same? This lesson describes the difference between the two as well as the effect of gravity on weight. Examples are used to teach you how to calculate weight based on mass and acceleration of gravity.

### 15. Identifying Action and Reaction Force Pairs

Good things often come in pairs, and forces are no exception. In this lesson you'll explore Newton's second and third laws of motion to understand how action and reaction pairs affect objects interacting with each other.

### 16. The Normal Force: Definition and Examples

The normal force is also called the contact force because it only exists when objects are touching. In this lesson, we will investigate what the normal force is and how to calculate it on flat and inclined surfaces.

### 17. Friction: Definition and Types

You experience friction all the time, and you should be glad you do! Friction helps keep stationary objects in place as well as slow moving objects down as they slide across a surface. This lesson identifies what friction is and explains the two ways we find this force on earth.

### 18. Inclined Planes in Physics: Definition, Facts, and Examples

If an object is not horizontal to the ground, it may be on an inclined plane. We need to adjust both the calculations and the free-body diagram when determining the net force on an object on an inclined plane. Learn how in this lesson.

### 19. Hooke's Law & the Spring Constant: Definition & Equation

After watching this video, you will be able to explain what Hooke's Law is and use the equation for Hooke's Law to solve problems. A short quiz will follow.

### 20. Centripetal Force: Definition, Examples & Problems

After watching this video, you should be able to explain what centripetal force is, identify the centripetal force in a particular situation, and solve problems using the centripetal force equation. A short quiz will follow.

### 21. Compressive Stress: Definition, Formula & Maximum

Compressive stress is a consideration in understanding how a material performs when under pressure. In this lesson, learn what compressive stress is as well as the formula necessary for calculating it.

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### Other Chapters

Other chapters within the Physics 101: Help and Review course

- Introductory Physics: Help and Review
- Vectors: Help and Review
- Kinematics: Help and Review
- Work and Energy in Physics: Help and Review
- Linear Momentum: Help and Review
- Equilibrium and Elasticity: Help and Review
- Sound and Light: Help and Review
- Fluids in Physics: Help and Review
- Laws of Thermodynamics: Help and Review
- Electrostatics: Help and Review
- Circuits in Physics: Help and Review
- The Physics of Magnetism: Help and Review
- Wave Optics: Help and Review
- Classical Relativity: Help and Review
- Modern Physics: Help and Review
- Using Physics Formulas