# friction

Friction is a force that holds back the movement of a sliding object. That’s it. Friction is just that simple. You will find friction everywhere that objects come into contact with each other. The force acts in the opposite direction to the way an object wants to slide.

Measuring Friction – Higher coefficient of friction compared to lower coefficient of friction. Measures of friction are based on the type of materials that are in contact. Concrete on concrete has a very high coefficient of friction. That coefficient is a measure of how easily one object moves in relationship to another. When you have a high coefficient of friction, you have a lot of friction between the materials.

Do It
Challenges for you to work on…

• Friction – Learn how friction causes a material to heat up and melt. Rub two objects together and they heat up. When one reaches the melting temperature, particles break free as the material melts away. A “virtual” thermometer is used to show the increase in temperature as books are rubbed against each other.
• Put some sand in two styrofoam cups taped together, Thermometer inserted in side. Record temperature. Shake vigorously and record temperature.
• Friction – Experiment how the movement of vehicles responds to different surfaces and levels of resistance in this friction game. Which surface slows a vehicle down more – vinyl, wood, carpet or ice? Try and get the car to the end of the track using the principles and science information you learn about kinetic friction into action.
• Friction – conduct the experiments, then take the quiz.
• Litter Grabber – make a tool to help clean up your favorite places