AP Physics 1: Unit 0 Topic: Language of Physics Learning Goals: Compare and contrast object and system Define the make up of an object of a system of objects Define open and closed/isolated systems and apply appropriate conservation concepts Create a boundary for a system that is logical and practical Distinguish between scalar and vector quantities

Physics and Math In math your unknowns often equal numbers, while in physics our unknowns equal values. Two types of quantities we deal with are scalars and vectors (more on this later). Unknown values in math are often given the symbol x or y or z. In physics our quantities have specific symbols. We cannot call every unknown x.

describe, explain, justify, calculate, derive, what is, determine, sketch, plot, draw, label, design, and outline have precise meanings Describe and explain: require the ability to demonstrate and understanding of physics principles by providing an accurate and coherent description or explanation Justify: argument supported by evidence (ex:statements of physical principles, equations, calculations, data, graphs, and/or diagrams)

Calculate: student is expected to show work leading to a final answer which may be algebraic or numerical. Derive: students need to being their solution with one or more fundamental equations. The final answer, usually algebraic, is then obtained through the appropriate use of mathematics. What is and Determine: work need not necessarily be explicitly shown to obtain full credit (but showing work can help to obtain partial credit)

Sketch: draw a graph that illustrates key trends in a particular relationship (slope, curvature, intercept(s), or asymptote(s)). Scaling or specific data points are not required in a sketch Plot: draw the data points given in the problem on the grid provided using a scale and units (the scale and units may or may not be given) Draw and Label: Usually with forces. more specifics on this in NM unit 3 and others

Design or Outline: students are expected to provide an orderly sequence of statements that specifies the necessary steps in the investigation needed to reasonably answer the question or investigate the phenomenon.

Scalar vs. Vector Scalar values: Just have a magnitude (number value). Ex: distance, time, temperature. Scalar quantities do not require any special rules for add, sub, mult, or div. Vector values: Have magnitude (number value) and direction. Vector directions can be compass directions, + or - signs, or loads of other things. Special rules may apply when adding and subtracting (more on this on another day).

Conservation Call back What is the conservation of energy? What is the conservation of mass?

Objects vs. System When we treat “something” as an object, we are choosing to ignore the internal structure (if there is any) We have a system when the internal structure exists and must be taken into account. As we explore physical phenomena throughout the year we will need to take care as to what we are observing

One more thing about a system Oftentimes we will need to define what is included in our system. It is important to only include objects (aka “parts” of the internal structure) that make sense. This is a skill that will take time to develop.

Conservation Laws and Systems Closed (or isolated) systems do not exchange matter or energy with its environment (surroundings). Any of our conserved quantities would remain constant for this system. Open systems exchanged matter and energy with its surroundings. This exchange still follows (obeys) the conservation rules for the quantities we previously discussed.