HS - PS2.A (A) - Newton's Second Law of Motion - ASSIGNED (RC 4/14/2014)

Module: Newton’s Second Law of Motion

DCI: PS2.A (A) Newton’s second law accurately predicts changes in the motion of macroscopic objects.

PE: HS-PS2-1 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.]

The ideas here are: 

- Newton's second law can be used to predict changes in the motion of objects. 

So, this standard is more than simple calculations using the f=ma formula, although it will be perfectly acceptable to have 1-2 questions that do just that.  For the larger part of the formula, we will have to do exactly as the PE says.  We will provide students with data about the motion of objects, and students will have to use that data to 'prove' that Newton's 2nd law can describe the relationship between the data. 

Possible Question Starters: 

Here's a simple f=ma question...

"A box with a mass of 20 kg is pulled across a floor with a force of 50N.  If the force of friction is 10N, what is the acceleration of the box?" This may not be the best example though, because we have to subtract the force of friction (maybe we just change the picture?)

Here's one that's a little bit closer to addressing the PE, but doesn't quite get at supporting the claim. 

"The table shows the relationship between force and acceleration for a given mass. 

What force would be necessary to accelerate this mass to 25 m/s2?

correct answer = 125 N