Question

friction warm-up

1. review the definition of friction.
2. consider the two events and answer the questions.

friction: a force between an object and the surface it is moving over
imagine you push a book across an incredibly slippery surface. it slides right across because there is no friction. next, you push
the same book across a rougher surface that exerts friction.

1. will the velocity of the book change as it moves across the surface with no friction? explain your answer.

Explanation:

To determine if the velocity of the book changes on a frictionless surface, we use Newton's first law of motion (the law of inertia). Newton's first law states that an object in motion will stay in motion with a constant velocity (same speed and direction) unless acted upon by a net external force. In the case of the book on a frictionless surface, once you push it (applying an initial force to set it in motion), there is no friction (a force that would oppose its motion) and no other net external force mentioned (assuming a horizontal surface, normal force and gravity balance). So, without a net external force, the book's velocity (speed and direction) will remain constant.

Answer:

No, the velocity of the book will not change as it moves across the surface with no friction. According to Newton's first law of motion, an object in motion will maintain a constant velocity (constant speed and direction) unless a net external force acts on it. On a friction - less surface, there is no net external force acting on the book (after the initial push to set it in motion) to change its velocity.