Chapter 2: Problem 3

A person places a book on the roof of a car and drives off without remembering to remove it. As the book and the car move down a street at a steady speed, there are two horizontal forces acting on the book. What are they?

Short Answer

Expert verified

Answer: The two horizontal forces acting on the book are friction (F_f) and air resistance (F_a). Friction prevents the book from sliding off the car's roof, while air resistance opposes the motion of the book. These forces balance each other, allowing the book to remain on the car's roof as the car moves at a steady speed.

Step by step solution

Identify the forces acting on the book

In this situation, there are two horizontal forces acting on the book: friction and air resistance. These forces are responsible for keeping the book on the roof of the car while it is moving.

Understand the role of friction

Friction is the force that opposes the relative motion between two surfaces in contact. In this case, friction acts between the book and the car's roof. When the car is moving, the friction force between the book and the car's roof prevents the book from sliding off. The friction force (F_f) is directly proportional to the normal force (N) and can be calculated using the equation: F_f = μ * N where μ is the coefficient of friction between the book and the car's roof.

Understand the role of air resistance

Air resistance is the force exerted by air on the object moving through it, which opposes the motion of the object. In this case, as the car moves with the book on its roof, the air exerts a resistive force on the book, pushing it backwards. This force (F_a) depends on the speed of the car, the cross-sectional area of the book, and the density of air. Since the car is moving at a steady speed, the friction force should balance the air resistance. Otherwise, if the forces were not balanced, the book would either fall off the car or accelerate along with the car.

Conclusion

In the given situation, there are two horizontal forces acting on the book: friction (F_f) between the book and the car's roof, and air resistance (F_a), which opposes the motion of the book. These forces balance each other, allowing the book to remain on the car's roof as the car moves down the street at a steady speed.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

A person places a book on the roof of a car and drives off without remembering to remove it. As the book and the car move down a street at a steady speed, there are two horizontal forces acting on the book. What are they?

Short Answer

Step by step solution

Identify the forces acting on the book

Understand the role of friction

Understand the role of air resistance

Conclusion

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Physics Textbooks

Engineering Physics

Physical Quantities And Units

Mechanics and Materials

Atoms and Radioactivity

Magnetism

Conservation of Energy and Momentum

Study anywhere. Anytime. Across all devices.