Ch 4: Force and the Laws of Motion

About This Chapter

Watch video lessons on force and the laws of motion and learn about Newton's laws, types of force, action and reaction and more. These video lessons are short and engaging and make learning easy!

Force and the Laws of Motion - Chapter Summary and Learning Objectives

You'll explore Newton's laws of motion in this chapter and find out how these laws are used to understand and explain weight, mass and gravity concepts. Experienced instructors teach you about friction, centripetal force and net force. You'll learn how to measure the spring constant and identify action and reaction force pairs. After you've watched all the lessons in this chapter, you'll be familiar with:

  • Difference between inertia and mass
  • Contact and non-contact forces
  • Methods for determining net force of an object
  • Relationship between force and acceleration
  • Definition of inclined planes

Video Objectives
Newton's First Law of Motion: Examples of the Effect of Force on Motion Describe the interaction between force and motion and examine some applications for Newton's first law.
Distinguishing Between Inertia and Mass Explain how mass is a quantity that is solely dependent on the inertia of an object.
Mass and Weight: Differences and Calculations Differentiate between mass and weight. Calculate the weight of an object of known mass.
State of Motion and Velocity Examine how the state of motion of an object is defined by its velocity.
Force: Definition and Types Identify forces in both the contact and non-contact categories.
Forces: Balanced and Unbalanced Assess how balanced and unbalanced forces affect object movement.
Free-Body Diagrams Describe how to set up and use a free body diagram to solve problems.
Net Force: Definition and Calculations Calculate net force and use diagrams to visually represent forces acting on an object.
Newton's Second Law of Motion: The Relationship Between Force and Acceleration Understand how to calculate for acceleration and force and describe the relationship between these concepts.
Determining the Acceleration of an Object Identify the variables needed to determine the acceleration of an object.
Determining the Individual Forces Acting Upon an Object Use free-body diagrams to identify the forces acting on an object.
Air Resistance and Free Fall Describe the effect of air resistance on the velocity of free falling objects.
Newton's Third Law of Motion: Examples of the Relationship Between Two Forces Demonstrate how objects accelerate because of force and apply Newton's third law.
Newton's Laws and Weight, Mass & Gravity Use Newton's laws to understand the concepts of weight, mass, and gravity.
Identifying Action and Reaction Force Pairs Explain how objects interacting with each other are affected by action and reaction force pairs.
The Normal Force: Definition and Examples Describe normal force and explain why it's known as the support force.
Friction: Definition and Types Discuss the two types of friction force - static friction and sliding friction.
Inclined Planes in Physics: Definition, Facts, and Examples Describe an inclined plane and explain the forces acting on an object on an inclined plane.
Hooke's Law and the Spring Constant: Definition and Equation Define Hooke's law and measure the spring constant.
The Centripetal Force Requirement: Definition, Examples, & Problems Describe centripetal force and explain how it is calculated. Solve problems involving calculations of centripetal force.

21 Lessons in Chapter 4: Force and the Laws of Motion
Test your knowledge with a 30-question chapter practice test
Newton's First Law of Motion: Examples of the Effect of Force on Motion

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.

Distinguishing Between Inertia and Mass

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.

Mass and Weight: Differences and Calculations

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.

State of Motion and Velocity

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.

Force: Definition and Types

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.

Forces: Balanced and Unbalanced

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.

Free-Body Diagrams

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.

Net Force: Definition and Calculations

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.

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

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.

Determining the Acceleration of an Object

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.

Determining the Individual Forces Acting Upon an Object

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.

Air Resistance and Free Fall

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.

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

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.

Newton's Laws and Weight, Mass & Gravity

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.

Identifying Action and Reaction Force Pairs

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.

The Normal Force: Definition and Examples

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.

Friction: Definition and Types

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.

Inclined Planes in Physics: Definition, Facts, and Examples

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.

Hooke's Law & the Spring Constant: Definition & Equation

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.

Centripetal Force: Definition, Examples & Problems

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.

Action and Reaction Forces: Law & Examples

21. Action and Reaction Forces: Law & Examples

Action force is force acting in one direction. Reaction force is force acting in the opposite direction. Learn more about Newton's Third Law as it explains action and reaction forces through several examples, and test your knowledge with quiz questions.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
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Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
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