# Friction

Topics: Friction, Force, Mass Pages: 13 (3850 words) Published: August 19, 2013
Friction

Friction
Abstract
Students learn the principles of friction by demonstrating the effect weight, angle and gravity on the speed of movement of objects. of

Equipment
1. Friction Boards 2. Weights 3. Velcro Ball Game 4. Drill 5. ¾” Dowels 6. Rope 7. 3 x 8’ Flat Board 8. Styrofoam Boards 9. Bucket 10. Beer Glass 11. Decorations for Tortoise 12. Hairspray 13. Bennie Beads 14. Velcro 15. Hand Held Lenses 16. Drill Board

This activity is suitable for Middle and High School Students.

State Standards Met
Standard 1 – Analysis, Inquiry, and Design Standard 4 – Physical Setting and Living Environment Standard 7 – Interdisciplinary Problem Solving

Introduction
Friction is a part of our everyday life. Nearly every movement we make involves friction, and we have instinctively learned to take advantage of friction, or the lack of friction, since our childhood. Simple devices that rely on friction are everywhere around us. This workshop will help you see and appreciate the role of friction. As we study friction, lets also think about the differences between what scientists do and what engineers do. Scientists and engineers have been studying friction and its effects for a very long time. Engineers in particular have a real "love-hate" relationship with friction. For many jobs, an engineer must fight against friction and its effects through careful, clever design. In this workshop, we'll talk about the wedge and the wheel -- the ancient engineers' tremendously successful approach to friction. Roughly speaking, the scientist's role is to understand friction, what causes it and how those causes can be controlled. The engineer's role is to anticipate friction's part in the task at hand, and to use friction to the best advantage in the design of materials, machines, and experiments.

In this workshop, you will be a scientist, doing experiments to learn about friction and thinking about how it works; and then you will be an engineer when you design your own car to win a "slow" race down a ramp. You'll learn that there is no practical way to eliminate friction. Like the tortoise in the famous story, friction always "wins," eating away at energy you put into motion, slow and steady. Sooner or later, friction will cause the motion to stop. Ultimately, friction wins! Support for Cornell Center for Materials Research is provided through NSF Grant DMR-0079992 Copyright 2003 CCMR Educational Programs. All rights reserved.

1

What is friction?

Friction is the force that opposes sliding motion. It is the resistance to the movement of one body in relation to another body with which it is in contact. For example, if we try to slide a wooden block across a table, then friction acts in the direction opposite to the movement of the block.

Identifying the forces involved in friction
Let's talk about forces. Forces are pushes or pulls. Understanding forces is very important to many physicists and engineers. Researchers have spent a great deal of time defining a "language" of forces. We'll define some of the language of forces in this program. Forces act in a certain direction. Think about gravity. What direction does gravity always act in? _______ If something is not moving, all the forces on it are balanced: not only the amount of force, but also the direction. Did you say that gravity acts down? Good. Now, if there is a book on a table, and gravity is pulling down on the book, what sort of force is the table exerting on it? Gravity

Table

The table pushes up with exactly the same force that gravity pushes down. That force is equal to the weight of the book. Now, suppose that the table is at an angle, like an engineer's drawing board. Gravity still pushes down, but the table is not pushing straight up. It is pushing at an angle perpendicular to the table surface. Another force is needed to keep the book from sliding down the table: that's friction!

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