Mail Time: Does AP Physics 1 include rotational kinetic energy when rolling without slipping? And how carefully do I follow the AP1 course and exam description?

[Paraphrasing a correspondent...]

Dear Greg: I read online that, for AP Physics 1, "rolling kinetic energy is not required."  Is that correct?  What do AP1 students need to know about rolling?  Do you completely abide by the course and exam description in your AP1 course?

Rotational kinetic energy is definitely part of the AP Physics 1 exam!  Generally the problems involving rotation, like all AP1 problems, are qualitative and not quantitative.  That is, a student might be asked to describe the differences in energy conversion between a block sliding down a ramp, and a sphere rolling down a ramp; or, how an atwood's machine behaves differently with a massive vs. a low-mass pulley.  But here's the quotation I found in the course and exam description:

"A full dynamic treatment of rolling without slipping—for instance, using forces and torques to find the linear and angular acceleration of a cylinder rolling down a ramp—is not included in Physics 1."

A physics 1 student should be able to draw an energy bar chart for a cylinder rolling down a ramp, explain what forms of energy exist, and how we know they exist.  A Physics 1 student should be able to explain that the friction force of the ramp on the cylinder provides a torque around the cylinder's center of mass, and thus causes an angular acceleration, and thus causes the sphere to increase its rotational kinetic energy.  But the quantitative problem in which they write mgh = 1/2mv*2 + 1/2Iw^2, plug in w = v/R and the formula for the rotational inertia of a cylinder, and solve for v - that's an AP Physics C-mechanics question, not AP Physics 1.

I do cover everything in the course and exam description for physics 1, though in a unique order - for example, see this post or this post for examples of how I simplify concepts at the beginning of the course, and then add detail in the second half of the year.  And that course and exam description is not well written for an audience of teachers.  (It's much better as a guide for those who write the test, but for a teacher, it is too often impenetrable.)  For now, the best guide as to what you need to teach in your class is to look at recent exams; or, I've published my "fact sheet" in the 5 Steps to a 5 prep book.  That book is directly aligned to the exam, but everything is written in language that students and teachers can understand.

The College Board is publishing a new CED for the 2025 exam, or perhaps 2026 - no final word yet.  That one will be much more clearly written - I've seen a draft.  But for now, I'd use the 5 Steps book, or your own instincts from reading previous exams, as a guide for what's necessary in your AP1 course.