Physics Unit 2

Unit Overview – Circular Motion

The big picture stuff: Students are introduced to forces, including circular motion in grade 8, however, they do not learn to calculate and predict motions to this level of detail until high school.

Next Generation Science Standards – High School (NGSS-HS):

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.

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. All positions of objects and the directions of forces and motions must be described in an artibrarily chosen reference frame and arbitrarily chosen units of size.

Emphasize: balanced (Newton’s First Law) and unbalanced forces in a system, qualitative comparisons of forces, mass and changes in motion (Newton’s Second Law), frame of reference, and specification of units. Focus on forces and changes in motion in one-dimension in an inertial reference frame, and to change in one variable at a time.

Science and Engineering:

• 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.
• Apply scientific ideas or principles to design an object, tool, process or system.
• Construct and present oral and written arguments supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.
• Scientific knowledge is based upon logical and conceptual connections between evidence and explanations.

Crosscutting Concepts:

• Cause and effect relationships may be used to predict phenomena in nature or designed stems.
• Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales.
• The uses of technologies and any limitations on their use are driven by individual or societal needs, desires, and values; by the findings of scientific research; and by differences in such factors as climate, natural resources, and economic conditions.

California Science Standards - Physics:

1g. Students know circular motion requires the application of a constant force directed toward the center of the circle.

1i.* Students know how to solve two-dimensional trajectory problems.

Investigation and Experimentation Standards:

a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.

b. Identify and communicate sources of unavoidable experimental error.

c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.

d. Formulate explanations by using logic and evidence.