Page 216 - The Ontario Curriculum, Grades 11 and 12: Science, 2008 (revised)

Grade 12, College Preparation
c1. analyse common mechanical systems that use friction and applied forces, and evaluate their effectiveness in meeting social or environmental challenges;
c2. investigate forces, torque, work, coefficients of friction, simple machines, and mechanical advantage, and interpret related data;
c3. demonstrate an understanding of concepts related to forces and mechanical advantage in relation to mechanical systems.
C1. Relating Science to Technology, Society, and the Environment
C2. Developing Skills of Investigation and Communication
c. mechAnicAl SyStemS OVERALL EXPECTATIONS
By the end of this course, students will:
THE ONTARIO CURRICULUM, GRADES 11 AND 12 | science
SPECIFIC EXPECTATIONS
By the end of this course, students will:
c1.1 analyse advantages and disadvantages of friction within mechanical systems in real-world situations, as well as methods used to increase or reduce friction in these systems (e.g., advantages of, and methods for increasing, friction on the surface of car tires and the soles of hiking boots; disadvantages of, and methods for reducing, friction between moving parts of artificial joints) [AI, C]
Sample issue: Hip replacement has become
an increasingly common surgical procedure. Artificial hips consist of separate pieces, made of low-friction materials, that are designed to mimic the movement of the ball and socket hip joint. As the artificial joint ages, however, wear debris can cause increasing friction and restrict movement in the joint.
Sample questions: What changes to the design of the bobsled have resulted in faster speeds in competition and improved steering and man- oeuvrability? How and why does an under- or over-inflated tire affect the performance of a motor vehicle? Why do the soles of athletic shoes differ depending on the purpose of the shoe? Why do race car tires have no treads?
c1.2 evaluate, on the basis of research, the effectiveness of a common mechanical system in addressing a social or environmental chal- lenge (e.g., prosthetic devices, bathtub lifts, high-efficiency heating and cooling systems) [IP, PR, AI, C]
Sample issue: In the nineteenth century, lift locks were built in Ontario to give boats access to unnavigable sections of waterways such as the Great Lakes and the Trent-Severn waterway. Although the locks were mechanically simple, they were also highly effective, and some con- tinue to be used to the present day.
Sample questions: Why were crumple zones and airbags added to cars? How have integrated mechanical systems such as pro- grammable thermostats improved energy efficiency in homes?
By the end of this course, students will:
c2.1 use appropriate terminology related to me- chanical systems, including, but not limited to: coefficients of friction, torque, mechanical advantage, work input, and work output [C]
c2.2 analyse, in qualitative and quantitative terms, the forces (e.g., gravitational, frictional, and normal forces; tension) acting on an object in one dimension, and describe the resulting motion of the object [AI, C]
c2.3 use an inquiry process to determine the factors affecting static and kinetic friction, and to de- termine the corresponding coefficient of friction between an everyday object and the surface with which it is in contact [PR, AI]
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