- #1
Balsam
- 226
- 8
Homework Statement
A small textbook is resting on a larger textbook on a horizontal desktop. You apply a horizontal force to the bottom book and both books accelerate together. The top book does not slip on the lower book. What forces causes the top book to accelerate horizontally?
Homework Equations
--
The Attempt at a Solution
The answer in the solutions manual says that the top book's inertia makes it want to move backwards. There is a force of static friction acting to prevent this attempted motion. It acts opposite the direction of attempted motion, forwards. So, the top book accelerates with the bottom book and doesn't slip.
But, I'm confused because, doesn't there need to be an applied force on an object for there to be attempted motion at all? There's no applied force acting on the top book that would explain it's attempted backwards motion. Do you always need an applied force to state that an object is attempting motion? Is there a fictitious force involved? This is a stupid question, but I'm just confused