EXPECTATIONS -- Before we start this unit you should:

  • be comfortable with the difference between velocity and acceleration

  • have a general understanding that an object experiencing an acceleration *must* also experience a force

  • understand that letters can be used in place of numbers to represent calculations


Students who demonstrate understanding can:

FORCE, MASS & ACCELERATION: Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

[Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, or a moving object being pulled by a constant force.]

[Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]


MOMENTUM: Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

[Clarification Statement: Emphasis is on the quantitative conservation of momentum in interactions and the qualitative meaning of this principle.]

[Assessment Boundary: Assessment is limited to systems of two macroscopic bodies moving in one dimension.]


HS-PS2-3: Apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.

[Clarification Statement: Examples of evaluation and refinement could include determining the success of the device at protecting an object from damage and modifying the design to improve it. Examples of a device could include a football helmet or a parachute.]

[Assessment Boundary: Assessment is limited to qualitative evaluations and/or algebraic manipulations.]

GRAVITY: Use mathematical representations of Newton’s Law of Gravitation to describe and predict the gravitational forces between objects.

[Clarification Statement: Emphasis is on both quantitative and conceptual descriptions of gravitational fields.]

[Assessment Boundary: Assessment is limited to systems with two objects.]


Disciplinary Core Ideas

PS2.A: Forces and Motion

 Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object.

 If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system.

Newton’s second law accurately predicts changes in the motion of macroscopic objects.


PS2.B: Types of Interactions

 Newton’s law of universal gravitation provides the mathematical models to describe and predict the effects of gravitational force between distant objects.

 Forces at a distance are explained by fields permeating space that can transfer energy through space.

PS3.A: Definitions of Energy

 Criteria and constraints also include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.

ETS1.C: Optimizing the Design Solution

 Criteria may need to be broken down into simpler ones that can be approached systematically, and decisions about the priority of certain criteria over others (tradeoffs) may be needed.

Science and Engineering Practices

Planning and Carrying Out Investigations:

  • Planning and carrying out investigations to answer questions or test solutions to include investigations that provide evidence for and test conceptual, mathematical, physical and empirical models.

  • Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence and refine the design accordingly.

  • Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

  • Simple computational simulations are created and used based on mathematical models of basic assumptions.

  • Use mathematical representations of phenomena to describe explanations.

  • Apply scientific ideas to solve a design problem, taking into account possible unanticipated effects.


  • Connections to Nature of Science Science Models, Laws, Mechanisms, and Theories Explain Natural Phenomena

  • Theories and laws provide explanations in science.

  • Laws are statements or descriptions of the relationships among observable phenomena.