The Force of Friction
Friction is involved in many aspects of skateboarding.
In the first of two lessons of this curricular unit, students are introduced to the concept of friction as a force that impedes motion when two surfaces are in contact. Student teams use spring scales to drag objects, such as a ceramic coffee cup, along a table top or the floor, measuring the frictional force that exists between the moving object and the surface it slides on. By modifying the bottom surface of the object, students find out what kinds of surfaces generate more or less friction.
Friction is involved in many aspects of skateboarding. For example, while the wheel bearings should produce little friction, enough friction is needed between the wheels and the floor to keep the board from skidding during tight turns.Engineers must understand how friction affects a wide range of situations as they design consumer products, such as ski bottoms in which friction is a disadvantage and hiking boots where friction provides traction.
- CCSS.Math.Content.6.NS.B.3 Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.
Grade 6
Do you agree with this alignment? - CCSS.Math.Content.6.SP.B.5 Summarize numerical data sets in relation to their context, such as by:
Grade 6
Do you agree with this alignment? - CCSS.Math.Content.6.SP.B.5a Reporting the number of observations.
Grade 6
Do you agree with this alignment? - CCSS.Math.Content.6.SP.B.5b Describing the nature of the attribute under investigation, including how it was measured and its units of measurement.
Grade 6
Do you agree with this alignment?
- MS-PS2-2 Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.
Grades 6-8
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.Do you agree with this alignment?
- Science knowledge is based upon logical and conceptual connections between evidence and explanations.Do you agree with this alignment?
Disciplinary Core Ideas- The motion of an object is determined by the sum of the forces acting on it; if the total force on the object is not zero, its motion will change. The greater the mass of the object, the greater the force needed to achieve the same change in motion. For any given object, a larger force causes a larger change in motion.Do you agree with this alignment?
- All positions of objects and the directions of forces and motions must be described in an arbitrarily chosen reference frame and arbitrarily chosen units of size. In order to share information with other people, these choices must also be shared.Do you agree with this alignment?
Crosscutting Concepts- Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales.Do you agree with this alignment?
Do you agree with this alignment? - Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.
- Day 1-2: Discovering Friction lesson
- Day 3: Sliding and Stuttering activity
- Day 4-6: Factors Affecting Friction lesson
- Day 7: Does Contact Area Matter? activity
- Day 8: Does Weight Matter? activity
Contributors
Mary R. Hebrank
Supporting Program
Engineering K-PhD Program, Pratt School of Engineering, Duke University
Acknowledgements
This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
The lessons and associated activities of this curricular unit were originally published, in modified form, by Duke University's Center for Inquiry Based Learning (CIBL). Visit http://www.ciblearning.org/ for information about CIBL and other resources for K-12 science and math teachers.
Copyright
2013 by Regents of the University of Colorado; original © 2004 Duke University