In Cambridge, we believe that by introducing students to physics as Freshman we are setting a foundation of knowledge that will allow them greater success in chemistry and biology. All 9th graders begin their time at CRLS in a heterogeneously grouped physics course, with an honors option.
In Grade 9 Physics, instructional time should focus on four critical areas:
- Forces and motion;
- Forms of energy;
- Electrical and magnetic energy; and
- Sound and light energy
Unit
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Learning Goals |
Motion
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- Explain why variables are vectors or scalars
- Describe relationships between displacement, distance, velocity, speed, and acceleration
- Find velocity or time given acceleration.
- Describe the motion shown in a position-time or velocity-time graph with two or more segments (limited to constant velocity for position-time)
- Interpret complex graphs Draw graphs of particular situations
- Calculate acceleration (slope) from a velocity-time graph
- Calculate distance traveled from a velocity-time graph in which the velocity changes uniformly
- Describe how Newton’s Laws relate to common situations (i.e. seatbelts)
- Recognize situations in which force or weight needs to be calculated as the first step of a problem
- Solve simple two-step problems involving force and acceleration
- Draw free-body diagrams of objects with forces in two-dimensions (right angles only). Use information from a problem to draw a free-body diagram.
- Describe the affect of friction on the motion of an object
- Make qualitative predictions about the motion of objects in collisions
- Make predictions about how the gravitational force changes when mass and distance are changed
- Conceptually describe forces in uniform circular motion
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| Electricity |
- Explain how electrons are transferred when objects are charged by friction or contact.
- Explain the cause of polarization and give an example.
- Understand how conductors and insulators affect the flow of electrons.
- Determine the net charge on an ion.
- Solve Coulomb’s Law formula for F with or without using scientific notation.
- Qualitatively describe the relative effects of distance and charge on the electric force.
- Describe the relationships between voltage, current and resistance. Apply V=IR to simple series circuits.
- Draw schematic diagrams of both series and parallel circuits. Describe what happens when a circuit is open.
- Build series and parallel circuits that include switches. Differentiate behavior of series and parallel circuits.
- Describe conceptually the relationships between P, I, and V.
- Solve two-step electric circuit problems involving P=IV and V=IR.
- Recognize that moving electric charges produce magnetic forces and that moving a magnet produces an electric force.
- Give examples of applications of electromagnetism (motors and generators).
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Waves
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- Define pitch and volume with wave properties
- Draw wave graphs with a given period, frequency and amplitude
- Draw a graph of frequency versus wavelength
- Describe the motion of the medium in transverse and longitudinal waves
- Draw transverse and longitudinal waves
- Compare sound graphs based on frequency (pitch) and amplitude (volume)
- Change the frequency of a musical instrument
- Give an example that compares the speed of sound in two materials
- Explain and/or draw why frequency of a wave seems to change based on the motion of a sound source or receiver
- Compare and contrast sound and light waves
- Understand how the properties of mechanical and electromagnetic wave affect their use in outer space
- Compare incident and reflected rays with respect to the normal
- Relate the change in angle of a light ray to a change in speed of light.
- Use c = fλ to solve for frequency or wavelength
- For each section of the electromagnetic spectrum, describe at least one way that humans interact with it.
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| Energy |
- Explain with examples how work affects gains or losses in an object’s mechanical energy. Explain qualitatively how force and distance affect work done.
- Solve two-step problems (i.e. calculating weight to solve for work or solving for work and then power)
- Compare two objects based on their power output.
- Solve two-step problems (i.e. compare the power of two objects or calculate work in order to find power)
- Explain that total energy includes not only mechanical, but also includes thermal, chemical, electrical, etc.
- Use PE = mgh to solve for mass, acceleration of gravity, or height.
- Use KE = 1/2mv2 to solve for mass
- Interpret and explain heat and temperature graphs
- Distinguish between temperature and total heat energy
- Explain what would happen to a material if its temperature dropped to absolute zero
- Define specific heat
- Use Q = mcΔt to solve for mass, specific heat, or change in temperature
- Explain, on a molecular level, the process of heat transfer in each of the three methods
- Identify factors that affect the rate of heat transfer (i.e. lightness or darkness of an object affects how well it absorbs radiation)
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