MS - PS2.A (B) - Changes in Motion, Force, and Direction - FINAL (WND 1/22/2014)

Module: Changes in Motion, Force, and Direction

DCI: PS2.A (B) 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.

PE: MS-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.

 [Clarification Statement: Emphasis is on 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.] [Assessment Boundary: Assessment is limited to forces and changes in motion in one-dimension in an inertial reference frame and to change in one variable at a time. Assessment does not include the use of trigonometry.]

The ideas we see in this standard are: 

- the motion of an object is determined by the sum of forces acting on that object

- if the total force on the object is not zero, the motion of the object will change

- objects with more mass require more force to achieve the same change in motion. 

- for any given object, a larger force causes a larger change in motion. 

We can get away with one or two free body diagrams, then we will have to ask about investigations into forces acting on objects. 

Possible Question Starters:

"Which of the following objects will resist a change in motion?"

"Students applied different forces to objects with different masses to achieve the same change in motion.  Which of the following graphs best represents their results?"