Types of Forces: Informational Text, Images, and Assessment

Ask questions to determine cause and effect relationships of electric or magnetic interactions between two objects not in contact with each other. Examples of an electric force could include the force on hair from an electrically charged balloon and the electrical forces between a charged rod and pieces of paper; examples of a magnetic force could include the force between two permanent magnets, the force between an electromagnet and steel paperclips, and the force exerted by one magnet versus the force exerted by two magnets. Examples of cause and effect relationships could include how the distance between objects affects strength of the force and how the orientation of magnets affects the direction of the magnetic force. Assessment is limited to forces produced by objects that can be manipulated by students, and electrical interactions are limited to static electricity.

Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects. Examples of evidence for arguments could include data generated from simulations or digital tools; and charts displaying mass, strength of interaction, distance from the Sun, and orbital periods of objects within the solar system. Assessment does not include Newton’s Law of Gravitation or Kepler’s Laws.

Ask questions about data to determine the factors that affect the strength of electric and magnetic forces. Examples of devices that use electric and magnetic forces could include electromagnets, electric motors, or generators. Examples of data could include the effect of the number of turns of wire on the strength of an electromagnet, or the effect of increasing the number or strength of magnets on the speed of an electric motor. Assessment about questions that require quantitative answers is limited to proportional reasoning and algebraic thinking.

Support an argument that the gravitational force exerted by Earth on objects is directed down. “Down” is a local description of the direction that points toward the center of the spherical Earth. Assessment does not include mathematical representation of gravitational force.

Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact. Examples of this phenomenon could include the interactions of magnets, electrically-charged strips of tape, and electrically-charged pith balls. Examples of investigations could include first-hand experiences or simulations. Assessment is limited to electric and magnetic fields, and limited to qualitative evidence for the existence of fields.